CBSE Class 9 Science Practicals

Please refer to attached file for CBSE Class 9 Science Practicals

Class 9 Science practical skills for CBSE: the importance of experiments, the Board's practical test scheme, the list of 15 experiments, categories of practical skills, the design of the 20 mark practical written paper, and three sample papers of 30 multiple choice questions each, with scoring keys and questionwise analysis.

1. INTRODUCTION

Experiments are a central feature of the scientific method. No theory or law, however refined it may look, is acceptable in science unless it is confirmed by experiment. Experiments are also the primary tool to investigate new domains of nature. Science progresses through a continual interplay of theory and experiment. We are all aware of the great experiments that changed the course of scientific progress: Galileo's experiments on inclined planes and pendula, Faraday's experiments on electricity and magnetism, Lavoisier's experiments on combustion, Mendel's experiments on genetics and Rutherford's experiments on radioactivity, to name a few.

Just as experiments are important for advancement in science, they are equally important for learning science. School science education must, therefore, have experiments as its important focus. Experiments aid learning of science in several ways. First, they convey to the students the right message that science is about the real world around us - it is not just a theoretical subject abounding in formal definitions, formulas and laws. The latter is also important, no doubt; but theory must not stand in isolation, it relates to the real world. Experiments connect the theoretical world of text books to the real concrete world of experience. Second, experience shows that experiments are a way to create interest in science among students. They attract students of a wide range of abilities. Once the interest in the subject is kindled, students begin to take interest in the more theoretical parts of the subject too and thus improve their overall competence in science. Third, experiments promote the basic skills and competencies involved in science: procedural and manipulative skills, observation skills, skills of representing and interpreting data and the accompanying conceptual and critical abilities. For these various reasons, it is widely accepted that school science curriculum must have a strong 'activity and experiment-based' component.

The importance of experiments in science education has been recognized in the national policy of education for the last several decades. In practice, however, despite many efforts, experiments have not received their due importance and emphasis in science teaching in our schools. The problem is complex and arises due to a combination of several factors. Two reasons are often cited for the lack of emphasis on experiments in our schools. First, experiments require a certain minimum infrastructure - a laboratory with certain basic equipments, recurring expenditure on consumables, etc. This minimum infrastructure is not always available in all schools in our country. Second, in view of the difficult logistics involved in assessing experimental work for the large number of school students, the assessment of experiments has not been as serious as that for the theory part of the curriculum. What is not assessed externally is usually marginalized in our school system. In short, lack of infrastructure and, more important, lack of proper assessment, have resulted in the unfortunate marginalization or neglect of experimental work in Indian schools.

2. THE BOARD'S INITIATIVE

The Central Board of Secondary Education has always been concerned about giving due emphasis to experiments in the schools and has taken several steps in this matter in the past. It tries to ensure that its affiliated schools have the necessary infrastructure to carry out the experiments prescribed in the syllabus for Classes IX and X. To make this feasible for all its schools, care is taken that the laboratory curriculum does not demand excessively costly equipment. In order to strengthen the assessment of practicals for Classes IX and X, CBSE has now decided to take a new initiative aimed at increasing the emphasis of practicals in schools, promoting seriousness in carrying out the practicals, and in making assessment of practicals even more uniform and reliable. Currently, the weightage given to theory and practicals at secondary level is 75% and 25% respectively. Besides, the practical examination is conducted at school level and the marks obtained by every student are indicated separately in the certificate issued by the Board.

As per the new scheme, theory and practical examination will have a weightage of 60% and 40% respectively. The practical examination will comprise of two components. One component of this practical examination will be in the form of a written test, to be conducted by the Board in Class X as an independent paper. This question paper will be of 20 marks and 1½ hour duration. It will aim at testing of practical skills through multiple-choice type questions. Each multiple-choice question will have four options, with only one of them as the correct option. The second component will also have a weightage of 20 marks but will be conducted at school level on the lines being followed presently.

The Board hopes that this initiative will be an important step not only to give experiments their due place in the subject of Science and Technology but also to promote, in general, an experimental culture in our school system.

LIST OF EXPERIMENTS - SCIENCE AND TECHNOLOGY - CLASS IX

1. To prepare
a) a true solution of common salt, sugar and alum
b) a suspension of soil, chalk powder and fine sand in water
c) a colloid of starch in water and egg albumin in water and distinguish between these on the basis of
i) transparency
ii) filtration criterion
iii) stability.

2. To prepare
a) a mixture
b) a compound
using iron filings and sulphur powder, and distinguish between these on the basis of
i) appearance i.e. homogeneity or heterogeneity
ii) behaviour towards a magnet
iii) behaviour towards carbon disulphide (a solvent)
iv) effect of heat.

3. To carry out the following chemical reactions and record observations. Also to identify the type of reaction involved in each case.
i) Iron with copper sulphate solution in water.
ii) Burning of magnesium in air.
iii) Zinc with dilute sulphuric acid.
iv) Heating of lead nitrate.
v) Sodium sulphate with barium chloride in the form of their solutions in water.

4. To determine the density of a solid (denser than water) by using a spring balance and a measuring cylinder.
5. To establish the relation between the loss in weight of a solid when fully immersed in (i) water (ii) kerosene, with the weight of liquid displaced by it by taking at least two different solids.
6. To study the variation in limiting friction between blocks of different masses and surfaces of different nature.
7. To measure the temperature of hot water as it cools and plot a temperature-time graph.
8. To study the variation in the time period (T) of a simple pendulum with its length (L) and to plot L-T² graph.
9. To prepare stained temporary mounts of a) onion peel, and b) human cheek cells, and to record observations and draw their labelled diagrams.
10. To identify parenchyma and sclerenchyma tissues in plants, striped muscle fibres and nerve cells in animals, from prepared slides and to draw their labelled diagrams.
11. To prepare methane gas by heating sodium acetate and soda lime and study its physical properties, i.e. colour, odour, solubility in water and its chemical properties like combustion and action on bromine water and alkaline potassium permanganate solution.
12. To identify the saturated and unsaturated organic compounds out of the following: a) Kerosene b) Vegetable oil c) Butter d) Carbon tetrachloride.
13. To test a) the presence of starch in a given food sample, and b) the presence of the adulterant metanil yellow in dal.
14. To study the adaptive features of xerophytes such as cactus, and hydrophytes such as water lily/ lotus. To draw labelled diagrams and record observations.
15. To observe and draw the given specimens earthworm, cockroach, bony fish and bird. For each specimen to record
a) one specific feature of its phylum
b) one adaptive feature with reference to its habitat.

CATEGORIES OF PRACTICAL SKILLS

A. Procedural and Manipulative Skills
- select appropriate apparatus/ instruments for performing the experiment
- know the limitations of the apparatus/ instruments regarding their size, least count and accuracy
- arrange/ assemble/ set and adjust the apparatus systematically
- handle the apparatus, instruments, chemicals carefully to avoid any damage or injury
- perform the experiment with reasonable efficiency and accuracy
- separate and remove desired parts of a specimen for detailed study without damaging
- use appropriate methods and materials for specimen mounting
- locate and rectify the errors in apparatus, instruments, etc.
- add chemicals in appropriate quantity
- dismantle the experimental set-up carefully
- practise the precautions in handling sensitive apparatus or chemicals or flame

B. Observational Skills
- find the least count of the instrument
- read the instrument correctly
- notice colour change, evolution of gases, formation of precipitates, chemical reactions, etc carefully
- notice the relevant details in the given specimens minutely
- locate the desired parts in a specimen accurately
- take observations carefully and in a systematic manner
- read graph correctly

C. Drawing Skills
- make proper observation tables
- draw circuit diagrams, ray diagram, experimental set-up, sketches, etc. correctly and proportionately
- label sketches and diagrams correctly
- draw graphs from observed data correctly

D. Reporting and Interpretative Skills
- make a proper plan for recording the observations
- record the observations/ data/ information correctly and systematically
- classify and categorize organisms
- make correct calculations/predictions
- use proper formulae and mode of summarising and reporting the result
- report the result using correct symbols, units, terms and chemical equations
- interpret the observations and results correctly

DESIGN OF THE QUESTION PAPER - SCIENCE AND TECHNOLOGY CLASS IX (PRACTICALS)

Time: 1 ½ hours
Maximum Marks: 20
The weightage of distribution of marks over different dimensions of the question paper shall be as follows

A. UNIT-WISE WEIGHTAGE

B. SKILL-WISE WEIGHTAGE
Most questions involve multiple skills, and it may not always be possible to precisely assign particular skills to a given question. The skill-wise weightage given in the table below should therefore be considered as only indicative of what is required in the question paper.

C. QUESTION-WISE WEIGHTAGE
All the 30 questions would be of the multiple choice variety having only one correct answer. First 20 questions will carry 0.5 mark each while rest of 10 questions will carry 1 mark each.

D. EXPECTED TIME
Approximate time for reading and answering one question: 2.5 minutes
Revision time: 15 minutes

E. DIFFICULTY-WISE WEIGHTAGE

SAMPLE QUESTION PAPER I

Time: 1 ½ hours
Maximum Marks: 20

INSTRUCTIONS:
1. Attempt all questions.
2. There are 30 multiple choice questions in total. Only one of the options in every question is correct.
3. The question paper consists of two parts - Part A and Part B. Each of the 20 Questions in part A carries 0.5 mark and each of the 10 questions in part B carries 1.0 mark.

SECTION - A

1. The following substances are added to water in a beaker as shown below. The mixture is stirred well. A true solution is found in the beaker [0.5 Mark]
(a) I
(b) II
(c) III
(d) IV

[Figure: Four beakers of water, each with a spoon adding a substance while stirring: [I] Kerosene, [II] Sugar, [III] Soap, [IV] Milk]

Answer: (b) II

1. Sugar dissolves completely in water and forms a true solution.

Teacher's Note:
a) Kerosene does not mix, soap and milk form colloids, and only sugar gives a clear solution.

2. When we start heating a mixture of sulphur powder and iron filings, we would observe that [0.5 Mark]
(a) sulphur starts melting.
(b) iron filings start melting.
(c) mixture becomes red hot.
(d) mixture evaporates.

Answer: (a) sulphur starts melting.

1. Sulphur has a lower melting point than iron.

Teacher's Note:
a) Sulphur melts at about 115°C, while iron melts at a far higher temperature.

3. When magnesium combines with oxygen it produces magnesium oxide that appears to be like [0.5 Mark]
(a) wood ash.
(b) chalk powder.
(c) table salt.
(d) powdered sugar.

Answer: (a) wood ash.

1. Magnesium oxide is a fine, white to greyish powder that looks like the ash left after burning wood.

Teacher's Note:
a) Compare the colour and fineness of the powder left after complete combustion.

4. When dilute sulphuric acid is added to zinc granules, you will observe that [0.5 Mark]
(a) a precipitate is formed.
(b) the reaction mixture turns yellow.
(c) the container becomes hot.
(d) bubbles start coming out from the surface of zinc granules.

Answer: (d) bubbles start coming out from the surface of zinc granules.

1. The reaction occurs at the contact point of the reactants and hydrogen gas is released as bubbles from the zinc surface.

Teacher's Note:
a) Zn + H₂SO₄ gives ZnSO₄ + H₂, and the hydrogen bubbles are the visible sign.

5. The correct observation when you mix barium chloride solution with sodium sulphate solution is that [0.5 Mark]
(a) a white precipitate is formed after some time.
(b) a yellow precipitate is formed after some time.
(c) a white precipitate is formed instantaneously.
(d) a yellow precipitate is formed instantaneously.

Answer: (c) a white precipitate is formed instantaneously.

1. Being an ionic reaction, precipitation of white barium sulphate is instantaneous.

Teacher's Note:
a) BaCl₂ + Na₂SO₄ gives BaSO₄ (white precipitate) + 2NaCl.

6. In the experiment to establish the relation between loss in weight of an immersed solid with the weight of water displaced by it, the correct setup is shown in figure [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four overflow cans A, B, C and D, each with a spout and a cube hanging in water. A and B use a thin cotton thread; C and D use a thick jute rope. The cube hangs at a different position in each can]

Answer: (b) B

1. The solid must be suspended by an inextensible string in the centre of the overflow can without touching its bottom.

Teacher's Note:
a) Use a thin cotton thread, not an elastic or thick rope, and keep the solid clear of the walls and bottom.

7. A given solid is weighed in air using a spring balance. It is then weighed by immersing it fully, in each of the three vessels containing water, as shown. Its weight when immersed, will be [0.5 Mark]
(a) least in vessel C.
(b) least in vessel B.
(c) least in vessel A.
(d) equal in all the three vessels.

[Figure: Three vessels of water: [A] a conical flask, [B] a beaker, [C] a tapering vessel with a scale on its side]

Answer: (d) equal in all the three vessels.

1. The loss in weight does not depend upon the shape of the vessel or the volume of water in it.

Teacher's Note:
a) Loss of weight equals the weight of the liquid displaced, which depends only on the volume of the solid.

8. A block of wood of mass 100 g is placed on a smooth table in the experimental set up used in the study of limiting friction. A student is asked to choose from the following:
(i) either pan of mass 30 g or 10 g
(ii) either slotted discs of mass 10 g each or of 2 g each.
The most suitable combination that she should choose would be [0.5 Mark]
(a) pan of 30 g and slotted discs of 10 g each.
(b) pan of 30 g and slotted discs of 2 g each.
(c) pan of 10 g and slotted discs of 10 g each.
(d) pan of 10 g and slotted discs of 2 g each.

Answer: (d) pan of 10 g and slotted discs of 2 g each.

1. A pan of mass 30 g may itself cause a 100 g block to slide on a smooth table. Also, a better least count is always desirable.

Teacher's Note:
a) Choose the lighter pan and the smaller slotted discs so that the pull can be increased in small steps.

9. Three students used different kinds of attachments while measuring limiting friction of a block placed over a table. Student A used a rubber band; B used a woollen thread; and C used a cotton thread. The best choice is [0.5 Mark]
(a) that of A.
(b) that of B.
(c) that of C.
(d) independent of the kind of attachment used.

Answer: (c) that of C.

1. We need an inextensible string, and a cotton thread does not stretch like rubber or wool.

Teacher's Note:
a) A stretching attachment gives a wrong measure of the pulling force.

10. The correct arrangement for taking temperature in the study of the temperature-time graph is shown in figure [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four calorimeters A, B, C and D with thermometers: in A the thermometer passes through a cork and dips vertically into the middle of the water; in B the bulb is near the bottom; in C the thermometer barely dips into the water; in D the thermometer is tilted, without a cork, against the side]

Answer: (a) A

1. The thermometer must be dipped vertically in the water, away from the bottom and sides of the calorimeter and close to the middle of the water.

Teacher's Note:
a) Keep the bulb fully immersed in the middle of the water and read it without touching the walls.

11. For the simple pendulum shown in the figure, the effective length is [0.5 Mark]
(a) AP
(b) OP
(c) CP
(d) CQ

[Figure: A simple pendulum hung from a clamp on a stand placed at the edge of a table. Points Q and P are marked near the top of the thread at the clamp; points A, O and C are marked on the bob, where A is the top of the bob, O the centre and C the bottom]

Answer: (b) OP

1. The length of the pendulum equals the length from the bottom of the suspension to the centre of the bob.

Teacher's Note:
a) Effective length is measured from the point of suspension to the centre of the bob.

12. The initial (A) and final (B) readings on a stop clock for 20 oscillations of a simple pendulum are shown in the figure. The time period of the simple pendulum is [0.5 Mark]
(a) 2.0 s
(b) 2.2 s
(c) 2.5 s
(d) 5.0 s

[Figure: Two stop clock dials, A (initial reading) and B (final reading); picture not clear in the PDF - add image]

Answer: (c) 2.5 s

1. The zero error of 5 seconds has to be added to the observed reading, so 20 oscillations take 50 s and T = 50 ÷ 20 = 2.5 s.

Teacher's Note:
a) Always correct the stop clock readings for zero error before dividing by the number of oscillations.

13. Nikita observed a slide of human cheek cells under a microscope in its (i) low magnifying power, (ii) high magnifying power settings. In the first setting, she must have observed [0.5 Mark]
(a) fewer cells in a darker field of view.
(b) more cells in a brighter field of view.
(c) more cells in a darker field of view.
(d) fewer cells in a brighter field of view.

Answer: (b) more cells in a brighter field of view.

1. Lower the magnifying power, more is the number of cells seen, in a brighter field of view.

Teacher's Note:
a) Higher magnification gives fewer cells and a darker field.

14. To observe cells in an onion peel, we must prepare the slide by mounting on it [0.5 Mark]
(a) crushed pulp of onion.
(b) dry scale leaf.
(c) green leaf of onion (spring onion)
(d) thin layer of fleshy leaf of onion.

Answer: (d) thin layer of fleshy leaf of onion.

1. To observe a living plant cell with a distinct nucleus, a thin peel from the fleshy leaf is the best material.

Teacher's Note:
a) Use a thin, transparent peel so that light passes through a single layer of cells.

15. The cellular component NOT seen while observing the slide of an onion peel under a compound microscope is [0.5 Mark]
(a) chromosomes.
(b) cell wall.
(c) nucleus.
(d) cytoplasm.

Answer: (a) chromosomes.

1. Chromosomes are not seen in interphase cells.

Teacher's Note:
a) Cell wall, cytoplasm and nucleus are visible; chromosomes appear only during cell division.

16. You are shown two slides of plant tissues: parenchyma and sclerenchyma. You can identify the sclerenchyma by the [0.5 Mark]
(a) location of nucleus.
(b) thickness of cell wall.
(c) size of cells.
(d) position of vacuoles.

Answer: (b) thickness of cell wall.

1. Parenchyma is thin walled, sclerenchyma is thick walled.

Teacher's Note:
a) Thick, lignified walls with a narrow cavity identify sclerenchyma.

17. Raj observed nerve cells under the microscope, and made the following sketch. The mistake in his drawing is the cyton with [0.5 Mark]
(a) cilia.
(b) dendrites.
(c) nucleus.
(d) cytoplasm.

[Figure: A sketch of a nerve cell drawn by Raj; picture not clear in the PDF - add image]

Answer: (a) cilia.

1. There are no cilia in the cyton.

Teacher's Note:
a) The cyton (cell body) has a nucleus, cytoplasm and dendrites but no cilia.

18. A student added only two drops of iodine to a rice extract in test tube A. Another student added a little rice extract to iodine solution in test tube B. They would then observe [0.5 Mark]
(a) a change of colour to blue black in test tube A but not in test tube B.
(b) a change of colour to blue black in test tube B but not in test tube A.
(c) a change of colour to blue black in both test tubes A and B.
(d) no change of colour in any test tube.

Answer: (c) a change of colour to blue black in both test tubes A and B.

1. Iodine and starch give a blue black colour, whichever is added to the other.

Teacher's Note:
a) Rice contains starch, so both test tubes show the blue black colour.

19. The proper experimental arrangement to collect methane gas is assembly [0.5 Mark]
(a) I
(b) II
(c) III
(d) IV

[Figure: Four assemblies I, II, III and IV for collecting methane gas; picture not clear in the PDF - add image]

Answer: (a) I

1. Methane is insoluble in water, so it is collected by downward displacement of water.

Teacher's Note:
a) Collect methane over water in an inverted gas jar filled with water.

20. Alkaline potassium permanganate solution is used to differentiate between saturated and unsaturated compounds. The container used to store this reagent should be a [0.5 Mark]
(a) colourless glass bottle.
(b) brown coloured bottle.
(c) white plastic bottle.
(d) sealed aluminium can.

Answer: (b) brown coloured bottle.

1. The reagent is sensitive to light, so it is stored in a brown bottle.

Teacher's Note:
a) Light-sensitive reagents are kept in amber or brown bottles.

SECTION - B

21. When an iron nail, rubbed with sand paper, is dipped in copper sulphate solution, we observe that copper gets deposited [1 Mark]
(a) first on the lower part of the nail and proceeds to the upper part.
(b) first on the upper part of the nail and proceeds to the lower part.
(c) on the entire surface of the nail.
(d) on the nail in small patches.

Answer: (c) on the entire surface of the nail.

1. The iron nail was rubbed before doing the experiment to expose the entire surface of the metal.

Teacher's Note:
a) A clean surface lets copper deposit evenly on the whole nail.

22. When solid lead nitrate is heated in a test tube, what is NOT observed during the reaction is: [1 Mark]
(a) a crackling sound is produced.
(b) a brown gas is produced.
(c) a light yellow solid is formed.
(d) swelling of lead nitrate takes place.

Answer: (d) swelling of lead nitrate takes place.

1. Lead nitrate decomposes into brown nitrogen dioxide gas and yellow lead oxide on heating, with a crackling sound; swelling is not observed.

Teacher's Note:
a) 2Pb(NO₃)₂ gives 2PbO + 4NO₂ + O₂ on heating.

23. The mass of a solid iron cube of side 4 cm is to be determined. Of the four spring balances available, the one best suited for this purpose would have [1 Mark]
(a) range = 0 to 100g, and least count = 1g.
(b) range = 0 to 100g, and least count = 5g.
(c) range = 0 to 1000g, and least count = 10g.
(d) range = 0 to 1000g, and least count = 25g.

Answer: (c) range = 0 to 1000g, and least count = 10g.

1. The cube has a volume of 64 cm³ and a mass of about 500 g, so the range must be 0 to 1000 g, and we must have the smaller least count, 10 g.

Teacher's Note:
a) Estimate the measurement first to select the range, then pick the smallest least count.

24. A student notes down the observations in the two spring balances and the measuring cylinder shown in the figure. From the given observations, the volume of the solid [1 Mark]
(a) is 64 cc
(b) is 36 cc
(c) is 28 cc
(d) 100 cc

[Figure: Two spring balances with the solid weighed in air and in water, and a measuring cylinder; picture not clear in the PDF - add image]

Answer: (c) is 28 cc

1. The volume of the solid (in cc) has the same magnitude as its loss in weight (in grams) in water. The readings in the figure are not readable in the PDF, so the printed key is used.

Teacher's Note:
a) Volume in cc equals the loss of weight in grams, since 1 cc of water weighs 1 g.

25. The table alongside gives the observations reported by two students X and Y for an experiment on the study of temperature-time graph. The experiment is likely to have been performed correctly by [1 Mark]
(a) X.
(b) Y.
(c) both X and Y.
(d) neither X nor Y.

Answer: (b) Y.

1. The rate of fall of temperature is faster first and slower later. Student Y's readings follow this pattern, while student X's fall gets faster with time.

Teacher's Note:
a) A cooling curve flattens as the water temperature approaches the room temperature.

26. Four samples of arhar dal (tuvar dal) were taken in four test tubes with some water in each and labelled P, Q, R and S. A few drops of the following were added to these test tubes: water to test tube P, HCl to test tube Q, NaOH to test tube R and alcohol to test tube S. We would be able to confirm adulteration of the dal with metanil yellow in test tubes [1 Mark]
(a) P and Q.
(b) Q and R.
(c) R and S.
(d) S and P.

Answer: (a) P and Q.

1. Metanil yellow is soluble in water and becomes pink with HCl.

Teacher's Note:
a) The yellow colour in water and the pink colour with HCl together confirm metanil yellow.

27. Samples of kerosene, vegetable ghee, groundnut oil and butter are taken in four different test tubes. A few drops of bromine water are added to each of the test tubes. You will observe the decolorisation of bromine water in the case of [1 Mark]
(a) kerosene and butter.
(b) kerosene and vegetable ghee.
(c) groundnut oil and butter.
(d) butter and vegetable ghee.

Answer: (c) groundnut oil and butter.

1. Unsaturated compounds decolourise bromine water. Groundnut oil is the unsaturated sample, and of the options only (c) contains it.

Teacher's Note:
a) Kerosene and vegetable ghee are saturated, so they do not decolourise bromine water.

28. Sana would not believe that the cactus in her garden was a xerophyte. Out of the following,
A. succulent leaves and deep root system
B. fleshy stem and spiny leaves
C. green stem and branched root system
D. woody stem and spiny leaves
the features of the cactus that show it is a xerophyte are [1 Mark]
(a) A and D.
(b) B and C.
(c) A, B and C.
(d) A, B, C and D.

Answer: (c) A, B and C.

1. The printed key (c) A, B and C is wrong. A cactus has no succulent leaves (the leaves are reduced to spines) and its stem is fleshy, not woody. The features that fit are B, a fleshy stem and spiny leaves, and C, a green stem and branched root system, so the correct option is (b).

Teacher's Note:
a) Features such as a fleshy stem, spiny leaves and a root system adapted to scarce water show that the cactus is a xerophyte.

29. Observe the pictures of honey bee and cockroach. The common feature that assigns them to the same phylum is [1 Mark]
(a) wings.
(b) three pair of legs.
(c) jointed appendages.
(d) antennae.

[Figure: Pictures of a honey bee (with wings) and a cockroach, shown dark in the PDF]

Answer: (c) jointed appendages.

1. All arthropods have jointed appendages.

Teacher's Note:
a) The phylum Arthropoda is defined by jointed legs.

30. A student found the posterior part of a male cockroach in the laboratory. The following sketch was made. The missing part in the sketch is [1 Mark]
(a) anal cerci.
(b) anal style.
(c) brood pouch.
(d) antennae.

[Figure: The posterior end of a cockroach abdomen showing several segments and a pair of long anal cerci projecting from the last segment, with a small notch between them]

Answer: (b) anal style.

1. Only male cockroaches have anal styles along with anal cerci.

Teacher's Note:
a) The sketch shows the abdomen tip with anal cerci; a male also has a pair of anal styles.

SCORING KEY FOR SAMPLE PAPER I

QUESTIONWISE ANALYSIS FOR SAMPLE PAPER I

P: Procedural skills; M: Manipulative skills; O: Observational skills; D: Drawing skills; R: Reporting and interpretative skills

SAMPLE QUESTION PAPER II

Time: 1 ½ hours
Maximum Marks: 20

INSTRUCTIONS:
1. Attempt all questions.
2. There are 30 multiple choice questions in total. Only one of the options in every question is correct.
3. The question paper consists of two parts - Part A and Part B. Each of the 20 Questions in part A carries 0.5 mark and each of the 10 questions in part B carries 1.0 mark.

SECTION - A

1. A student was asked to mix the white of an egg with water and stir well. The student observed that [0.5 Mark]
(a) a transparent solution is formed.
(b) a translucent mixture is formed.
(c) egg white settles down at the bottom.
(d) egg white floats on the surface of the water.

Answer: (b) a translucent mixture is formed.

1. Egg white forms a colloid, which looks translucent.

Teacher's Note:
a) Egg albumin in water is a colloid, not a true solution or a suspension.

2. We want to carry out a reaction of zinc granules with sulphuric acid. One bottle contains concentrated sulphuric acid and another bottle contains dilute sulphuric acid. The correct way of carrying out the reaction is to [0.5 Mark]
(a) use concentrated sulphuric acid.
(b) add water to concentrated sulphuric acid before using it.
(c) use dilute sulphuric acid.
(d) mix concentrated and dilute sulphuric acid and add water to it.

Answer: (c) use dilute sulphuric acid.

1. Adding water to concentrated sulphuric acid is not advisable, as it is highly exothermic, so the dilute acid is used directly.

Teacher's Note:
a) Always add acid to water, never water to acid.

3. To prepare iron sulphide, by heating a mixture of iron filings and sulphur powder, we should use a [0.5 Mark]
(a) copper dish.
(b) watch glass.
(c) china dish.
(d) petri dish.

Answer: (c) china dish.

1. A china dish avoids side reactions and breakage at high temperature.

Teacher's Note:
a) Glass breaks and copper reacts with sulphur, so a china dish is used.

4. We will observe a precipitation to occur in the solution used when [0.5 Mark]
(a) barium chloride is added to sodium sulphate.
(b) barium chloride is added to sodium chloride.
(c) sodium sulphate is added to sodium chloride.
(d) hydrochloric acid is added to to barium chloride.

Answer: (a) barium chloride is added to sodium sulphate.

1. Barium sulphate precipitate is white.

Teacher's Note:
a) Only barium chloride with sodium sulphate gives an insoluble salt, BaSO₄.

5. A student by mistake mixed iron filings and sulphur powder. He wanted to separate them from each other. The method you would advise him to use is to dissolve the mixture in [0.5 Mark]
(a) boiling water.
(b) cold water.
(c) carbon disulfide.
(d) kerosene.

Answer: (c) carbon disulfide.

1. Sulphur is soluble in carbon disulphide, while iron is not.

Teacher's Note:
a) Filter off the iron and evaporate the solvent to recover the sulphur.

6. The spring balance shown here is used to measure the mass of a given solid. The mass of the solid is [0.5 Mark]
(a) 115 g
(b) 118 g
(c) 120 g
(d) 125 g

[Figure: A spring balance with a scale in grams holding a solid; picture not clear in the PDF - add image]

Answer: (a) 115 g

1. The zero error has to be correctly accounted for. The balance reading in the figure is not readable in the PDF, so the printed key is used.

Teacher's Note:
a) Subtract or add the zero error of the spring balance before stating the mass.

7. The water level in a measuring cylinder, before and after immersing a solid in it, is shown in the figure. The volume of the given solid in, cc, is [0.5 Mark]
(a) 1.8
(b) 2.0
(c) 2.2
(d) 2.4

[Figure: Two measuring cylinders showing the water level before and after immersing the solid; picture not clear in the PDF - add image]

Answer: (c) 2.2

1. The correct reading of the lower meniscus has to be taken in both the cases. The cylinder readings are not readable in the PDF, so the printed key is used.

Teacher's Note:
a) Volume of the solid is the difference between the two readings of the lower meniscus.

8. The temperature-time graph obtained when a hot liquid is allowed to cool, is likely to resemble graph [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four temperature-time graphs: A is a curve that is almost flat at first and then falls steeply; B is a curve that falls steeply at first and then flattens; C is a straight line sloping downwards; D is flat, then falls along a straight line, then becomes flat again]

Answer: (b) B

1. The liquid cools faster first and slowly later on.

Teacher's Note:
a) A cooling curve falls steeply at first and then flattens.

9. Of the four experimental set-ups shown here to study temperature-time graph, the best one is [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four calorimeters A, B, C and D with thermometers fixed through a cork. A and B have a ring stirrer with a handle; C and D have only a thermometer]

Answer: (a) A

1. We need a stirrer and a thermometer correctly positioned without touching the sides of the calorimeter.

Teacher's Note:
a) Stir the water gently and keep the thermometer bulb in the middle of the water.

10. Student A counts the number of oscillations of a pendulum by counting the number of times it passes the mean position. Student B counts the number of times it reaches the extreme position on the right. Both calculate the time per oscillation (T) by dividing the total time by the number of oscillations counted. The value of T obtained by [0.5 Mark]
(a) student A will be correct.
(b) student B will be correct.
(c) both students A and B will be correct.
(d) neither student A nor student B will be correct.

Answer: (b) student B will be correct.

1. Student A will count twice the number of actual oscillations, because the bob passes the mean position twice in each oscillation, while student B counts one per oscillation.

Teacher's Note:
a) One oscillation is complete when the bob returns to the same extreme position.

11. For determining the time period of a simple pendulum, the bob should be suspended by means of a [0.5 Mark]
(a) fine cotton thread.
(b) thin copper wire.
(c) thin elastic string.
(d) woollen thread.

Answer: (a) fine cotton thread.

1. We must use an inextensible string in a simple pendulum.

Teacher's Note:
a) Elastic string and wool stretch, and wire is stiff.

12. Out of the following, the best choice for measuring the time period of a simple pendulum is [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four pendulums A, B, C and D swinging with dotted paths and three bob positions each. A wide swing in A has a bob marked as a spinning bob; B, C and D show other swings]

Answer: (b) B

1. The pendulum bob must be made to swing with a small amplitude, without spinning or moving in a circular path.

Teacher's Note:
a) Use a small angle of swing, about 10° to 15°, for accurate results.

13. Trupti was observing an onion peel stained with safranin under a microscope. The colour of the cell wall appeared [0.5 Mark]
(a) deep blue.
(b) black.
(c) pinkish red.
(d) yellow.

Answer: (c) pinkish red.

1. Safranin stains cellulose, so the cell wall appears pinkish red.

Teacher's Note:
a) Safranin gives a pinkish red colour to the cell walls.

14. While observing a thin section of a plant stem, four students sketched sclerenchyma as given below. The correct diagram is [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four sketches A, B, C and D of elongated plant cells with walls and, in some, a nucleus in the middle]

Answer: (c) C

1. Pits, non nucleated cells and thick cell walls are the characteristics of sclerenchyma.

Teacher's Note:
a) Sclerenchyma cells are dead, thick walled and have no living nucleus.

15. On the laboratory table were placed four watch glasses with labels A, B, C and D. Watch glass "A" had chalk powder, "B" had sago powder, "C" had common salt and "D" had powdered sugar. On adding two drops of iodine to the content of each watch glass, the one turning blue black will be [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

Answer: (b) B

1. Sago contains starch, which turns blue black with iodine.

Teacher's Note:
a) Starch is the only one of these four substances that gives the iodine test.

16. Seema bought arhar dal (tuar dal) from the market. On adding water to the dal the water became yellow in colour. She took a sample of this yellow water to the laboratory and added a few drops of HCl. The sample became pink. This confirmed that the adulterant added to the dal was [0.5 Mark]
(a) turmeric.
(b) metanil yellow.
(c) potassium dichromate.
(d) yellow dye.

Answer: (b) metanil yellow.

1. Aqueous metanil yellow with HCl turns pink.

Teacher's Note:
a) The pink colour with HCl is the test for metanil yellow.

17. To observe starch granules in potato under a microscope, freshly cut surface of potato was pressed on a slide. The stain that will show starch granules clearly is [0.5 Mark]
(a) methylene blue.
(b) iodine.
(c) safranin.
(d) eosin.

Answer: (b) iodine.

1. Iodine is the test for starch.

Teacher's Note:
a) Starch granules stain blue black with iodine.

18. When asked to prepare methane gas in the laboratory, four groups of students had set up apparatus as shown in I, II, III and IV. Only one group of students succeeded in getting the gas. This group was the one with [0.5 Mark]
(a) set-up I.
(b) set-up II.
(c) set-up III.
(d) set-up IV.

[Figure: Four hard glass test tubes, each clamped horizontally on a stand: I sodium acetate + soda lime, not heated; II sodium acetate + lime, heated; III sodium acetate + soda lime, heated; IV sodium carbonate + soda lime, heated]

Answer: (c) set-up III.

1. The correct combination of chemicals (sodium acetate and soda lime) and heating is essential.

Teacher's Note:
a) Methane is made by heating sodium acetate with soda lime, not with lime or sodium carbonate.

19. Most of the organic compunds are flammable in nature. The correct safety, symbol that is normally labelled on the bottles of such compounds is shown in figure. [0.5 Mark]
(a) I
(b) II
(c) III
(d) IV

[Figure: Four hazard symbols: I a skull with an explosion and radiation sign, II liquid dripping on a hand and a surface (corrosive), III a skull and crossbones (toxic), IV a flame (flammable)]

Answer: (d) IV

1. The flame symbol indicates that organic compounds are flammable.

Teacher's Note:
a) The flame hazard symbol warns of flammable material.

20. Noor wants to observe a spiracle of a cockroach. She should observe the region on its body shown by the label [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: A drawing of a cockroach seen from below, with four lines labelled A, B, C and D pointing to different regions of its body from head to abdomen]

Answer: (c) C

1. This is the correct location of spiracles.

Teacher's Note:
a) Spiracles are the openings on the sides of the thorax and abdomen.

SECTION - B

21. Four students were asked to observe the effect of heat on lead nitrate crystals. The teacher provided them with test tube holders, test tubes and solid lead nitrate. The students then started heating lead nitrate as shown below. The teacher stopped three of them for using a wrong procedure. The correct way of heating is shown in setup [1 Mark]
(a) I
(b) II
(c) III
(d) IV

[Figure: Four test tubes I, II, III and IV held in holders over a burner flame at different positions and angles; picture not clear in the PDF - add image]

Answer: (b) II

1. The tip of the flame is the hottest. The holder should hold the test tube at the top and the face should be away.

Teacher's Note:
a) Hold the test tube at an angle, near its mouth, with the mouth pointing away from everyone.

22. Four students used different ways of burning magnesium ribbon during an experiment as shown below. The correct way has been followed by student [1 Mark]
(a) I
(b) II
(c) III
(d) IV

[Figure: Four ways of burning magnesium ribbon: I and II held with fingers by hand over a flame, III held with tongs over a flame, IV not clear in the PDF]

Answer: (c) III

1. A pair of tongs is necessary to hold the burning ribbon.

Teacher's Note:
a) Never hold a burning magnesium ribbon with bare fingers or look directly at the flame.

23. You are given solid cubes of aluminium and iron, each of side 4cm, and two spring balances. Balance A has a range of 0 to 250 g and a least count of 2.5 g, while balance B has a range of 0 to 1000 g and a least count of 10 g. The preferred option for mass measurement would be to use [1 Mark]
(a) balance A for both the cubes.
(b) balance B for both the cubes.
(c) balance A for the aluminium cube and balance B for iron cube.
(d) balance A for the iron cube and balance B for aluminium cube.

Answer: (c) balance A for the aluminium cube and balance B for iron cube.

1. The aluminium cube is about 170 g, within the range of balance A, and the iron cube is about 500 g, which needs balance B. While preferring a smaller least count, we should estimate the range needed for a given measurement and select accordingly.

Teacher's Note:
a) Estimate the mass from density × volume before choosing the balance.

24. The readings of the spring balance will be [1 Mark]
(a) equal to each other in all cases A, B and C.
(b) equal to each other in cases A and C only.
(c) equal to each other in cases B and C only.
(d) different in every case.

[Figure: Three set-ups A, B and C of a solid hanging from a spring balance in vessels of water; picture not clear in the PDF - add image]

Answer: (c) equal to each other in cases B and C only.

1. The loss in weight of a fully immersed solid does not depend on the shape of the vessel or the volume of water in it. The figure is not readable in the PDF, so the printed key is used.

Teacher's Note:
a) Compare the cases where the solid is fully immersed; the reading then depends only on the solid.

25. A student observes that a block kept on a table, in the experimental set up used in the study of limiting friction, begins to move after adding 5g to the pan. The mass of the pan is 25g. If an identical block of the same mass is kept on the first block, the additional mass to be put in the pan, needed to just move the blocks, would most likely be [1 Mark]
(a) 10 g
(b) 20 g
(c) 30 g
(d) 40 g

Answer: (c) 30 g

1. The block just moves when the pull is 25 g (pan) + 5 g = 30 g. Doubling the mass doubles the limiting friction, so the pull needed is 60 g, which means 35 g in the pan besides the pan itself. As 5 g was already added, the additional mass to be put is 30 g.

Teacher's Note:
a) Limiting friction doubles when the normal reaction doubles.

26. Given below are four operations for preparing a temporary mount of human cheek cells:
(i) taking scraping from inner side of the cheek and spreading it on a clean slide
(ii) putting a drop of glycerine on the material
(iii) adding two or three drops of methylene blue
(iv) rinsing the mouth with fresh water and disinfectant solution.
The correct sequence of these operations is [1 Mark]
(a) i-ii-iii-iv
(b) iv-i-iii-ii
(c) iv-i-ii-iii
(d) i-iii-ii-iv

Answer: (b) iv-i-iii-ii

1. The mouth is to be disinfected first and glycerine is to be added last.

Teacher's Note:
a) Rinse, scrape, stain, then add glycerine and a cover slip.

27. You are viewing a prepared slide of striped muscle fibres from cockroach leg. When you focus the microscope, the striations appear pale and indistinct. To make the striations clearly visible, you would [1 Mark]
(a) slowly close the diaphragm to reduce the light.
(b) remove the mirror to cut out light.
(c) change the eye piece to increase magnification.
(d) replace the objective to decrease magnification.

Answer: (a) slowly close the diaphragm to reduce the light.

1. Reduction of light gives a better contrast.

Teacher's Note:
a) Closing the diaphragm increases contrast for pale, transparent structures.

28. A figure depicting parts of a neuron is given below. The correct identification of the labels 1, 2, 3, 4 respectively is [1 Mark]
(a) dendrite, cytoplasm, nissl granules, nerve fibre.
(b) cilia, endoplasmic reticulum, nucleoli, nerve fibre.
(c) dendrons, cell body, Nissl granuale, axon.
(d) dendrites, cyton, nucleus, axon.

[Figure: A neuron with four arrows: 1 and 2 pointing to parts at the cell body end, 3 pointing to the dot (nucleus) inside, and 4 pointing to a long process (axon)]

Answer: (d) dendrites, cyton, nucleus, axon.

1. This is the correct labelling of a neuron: dendrites, cyton (cell body), nucleus and axon.

Teacher's Note:
a) A neuron has dendrites, a cell body (cyton) with a nucleus, and an axon.

29. Samples of a few fats and oils were stored in the laboratory for performing experiments. One of the containers did not have any label. When tested, it was found that the unknown sample did not decolorize alkaline potassium permanganate solution. The sample could be [1 Mark]
(a) vanaspati ghee.
(b) mustard oil.
(c) linseed oil.
(d) castor oil.

Answer: (a) vanaspati ghee.

1. Vanaspati ghee is the only saturated substance in the list, so it does not decolourise the reagent.

Teacher's Note:
a) Only unsaturated compounds decolourise alkaline potassium permanganate.

30. The part that prevents loss of water and the part that stores water, in the plant shown in this drawing are [1 Mark]
(a) A and D
(b) B and A
(c) C and B
(d) D and C

[Figure: A hand-drawn cactus with flat fleshy pads bearing spines, with labels A, B, C and D pointing to different parts, and D pointing to the roots at the base]

Answer: (c) C and B

1. Leaves are modified into spines to lose less water from the plant body, and the fleshy stem stores water.

Teacher's Note:
a) Link each part of the cactus with its function in a dry habitat.

SCORING KEY FOR SAMPLE PAPER II

QUESTIONWISE ANALYSIS FOR SAMPLE PAPER II

P: Procedural skills; M: Manipulative skills; O: Observational skills; D: Drawing skills; R: Reporting and interpretative skills

SAMPLE QUESTION PAPER III

Time: 1 ½ hours
Maximum Marks: 20

INSTRUCTIONS:
1. Attempt all questions.
2. There are 30 multiple choice questions in total. Only one of the options in every question is correct.
3. The question paper consists of two parts - Part A and Part B. Each of the 20 Questions in part A carries 0.5 mark and each of the 10 questions in part B carries 1.0 mark.

SECTION - A

1. You have prepared four different mixtures in water using 1. charcoal powder, 2. chalk powder, 3. slaked lime and 4. detergent powder. If you filter these mixtures through a filter paper, there will be no residue left after filtration in the case of [0.5 Mark]
(a) charcoal powder.
(b) chalk powder.
(c) slaked lime.
(d) detergent powder.

Answer: (d) detergent powder.

1. Detergents form a colloidal solution in water and pass through the filter paper.

Teacher's Note:
a) Charcoal and chalk are suspensions, so they leave a residue.

2. The safest method to detect hydrogen gas produced in a reaction would be the method shown in [0.5 Mark]
(a) I
(b) II
(c) III
(d) IV

[Figure: Four test tubes I, II, III and IV containing reaction mixtures with different arrangements; picture not clear in the PDF - add image]

Answer: (a) I

1. The delivery tube should not touch the liquid.

Teacher's Note:
a) Test hydrogen by bringing a burning splinter to the mouth of the tube, which gives a pop sound.

3. To prepare a colloidal solution of starch we should [0.5 Mark]
(a) add starch powder to boiling water and cool.
(b) add starch powder to cold water and boil.
(c) heat starch powder, add it to cold water and then bring to boil.
(d) add a thin paste of starch to boiling water while stirring.

Answer: (d) add a thin paste of starch to boiling water while stirring.

1. A thin paste of starch enables colloid formation.

Teacher's Note:
a) Make a paste with a little cold water first, then pour it into boiling water with stirring.

4. Students were asked to study the reaction between barium chloride and sodium sulphate. Four different reports of the experiment are given below. Choose the correct one. [0.5 Mark]

Answer: (b) Mixed solutions of barium chloride and sodium sulphate. Thick white precipitate is formed.

1. The rate of reaction is faster in solutions, and BaSO₄ is white.

Teacher's Note:
a) Reactions between ionic salts need them in solution.

5. 100 mL of saturated copper sulphate solution was taken in a beaker. A small amount of iron filings was added to the beaker and left undisturbed overnight. The mixture was then filtered to obtain the residue. The colour of the residue was found to be [0.5 Mark]
(a) greenish blue.
(b) faint green.
(c) steel grey.
(d) reddish brown.

Answer: (d) reddish brown.

1. Copper is formed, having a reddish brown colour.

Teacher's Note:
a) Iron displaces copper from copper sulphate: Fe + CuSO₄ gives FeSO₄ + Cu.

6. The correct way of reading the liquid level is shown in [0.5 Mark]
(a) figure A.
(b) figure B.
(c) figure C.
(d) figure D.

[Figure: Four measuring cylinders A, B, C and D with the liquid level and the viewing position shown; picture not clear in the PDF - add image]

Answer: (a) figure A.

1. We need to position the eye in level with the lower part of the concave meniscus. The measuring cylinder must be placed on a flat surface.

Teacher's Note:
a) Read the bottom of the meniscus with the eye at the same level.

7. While determining the density of a copper piece using a spring balance and a measuring cylinder, Seema carried out the following procedure:
i. noted the water level in the measuring cylinder without the copper piece
ii. immersed the copper piece in the water
iii. noted the water level in the measuring cylinder with the copper piece inside it
iv. removed the copper piece from the water and immediately weighed it using a spring balance.
The wrong step in the procedure is [0.5 Mark]
(a) step (i).
(b) step (ii).
(c) step (iii).
(d) step (iv).

Answer: (d) step (iv).

1. It is wrong to weigh a wet copper piece, since the water sticking to it adds to its weight. The piece should be dried first.

Teacher's Note:
a) Weigh the solid in air first, or dry it well before weighing.

8. The correct experimental set-up for studying the variation of time period with length of a simple pendulum is shown in figure [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four set-ups A, B, C and D, each with a clamp on a stand fixed to a table and a bob on a thread displaced to one side at different heights above the floor]

Answer: (b) B

1. The bob has to be suspended in the correct way and must oscillate with a small amplitude without touching the table and the floor.

Teacher's Note:
a) Hang the bob from a split cork clamped on a stand and keep the amplitude small.

9. Four measuring cylinders with different least counts are shown in figures A, B, C and D. The most suitable cylinder for determining the volume of a cube of side nearly 1cm is [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four measuring cylinders A, B, C and D with different scales; picture not clear in the PDF - add image]

Answer: (d) D

1. The least count of the measuring cylinder must not be of the same order as, or larger than, the volume to be measured.

Teacher's Note:
a) A smaller least count gives a more accurate volume for a small solid.

10. The correct experimental setup for determining the mass of a solid in water is shown in figure [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four set-ups A, B, C and D with a solid hanging from a spring balance in water; picture not clear in the PDF - add image]

Answer: (b) B

1. The solid must be fully immersed without touching the bottom. Also, no part of the spring balance must dip into water.

Teacher's Note:
a) Hang the solid from the spring balance by a thin thread inside a beaker of water.

11. Three students made their simple pendulums as follows:
Student A used an iron bob and a woollen thread
Student B used an iron bob and a cotton thread
Student C used a wooden ball and a cotton thread
Student D used a wooden ball and a woolen thread.
The best choice is that of student [0.5 Mark]
(a) A.
(b) B.
(c) C.
(d) D.

Answer: (b) B.

1. It is important to use an inextensible string and it is preferable to use a small compact bob.

Teacher's Note:
a) A heavy, compact iron bob with a cotton thread swings with the least air resistance and no stretching.

12. The correct experimental set-up for studying limiting friction is shown in figure [0.5 Mark]
(a) I
(b) II
(c) III
(d) IV

[Figure: Four set-ups I, II, III and IV, each with a block on a table joined by a thread over the table edge to a hanging pan. In I the thread passes over a pulley at the edge and the pan hangs freely; in II to IV the thread, pulley or pan is arranged differently, and in IV the pan rests on a curved support]

Answer: (a) I

1. The string attached to the mass on the table must run parallel to the table surface and pass over a smooth pulley. The motion of the pan with weights must not be stopped by the leg of the table.

Teacher's Note:
a) Keep the string horizontal between the block and the pulley.

13. Human cheek cells stained in methylene blue and mounted in glycerine were observed with the help of a compound microscope. The components of the cell which would be seen are [0.5 Mark]
(a) cell wall, cytoplasm, nucleus.
(b) plasma membrane, cytoplasm, nucleus.
(c) plasma membrane, cytoplasm, nucleus, mitochondria.
(d) plasma membrane, cytoplasm, nucleus, mitochondria, golgi, lysosomes.

Answer: (b) plasma membrane, cytoplasm, nucleus.

1. These are the only components of the cell seen under a compound microscope.

Teacher's Note:
a) Animal cells have no cell wall, and the organelles are too small to be seen.

14. Observe the location and shape of the nuclei in the four drawings of the striated muscle fibres given below. The drawing that most resembles the slide of striated muscle fibre under the microscope is [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four drawings A, B, C and D of striated muscle fibres showing the location of nuclei; picture not clear in the PDF - add image]

Answer: (c) C

1. In striated muscle fibres the nuclei lie at the periphery.

Teacher's Note:
a) Look for several nuclei at the edge of the fibre and cross striations.

15. After preparing methane gas in the laboratory you must have tested that it burns in air. It is similar in appearance to the burning of [0.5 Mark]
(a) coal.
(b) a candle.
(c) magnesium.
(d) cooking gas.

Answer: (d) cooking gas.

1. Both methane and cooking gas burn with a blue flame.

Teacher's Note:
a) Cooking gas is a hydrocarbon mixture, so it burns like methane.

16. Bromine water, an important chemical reagent, is stored in a stoppered [0.5 Mark]
(a) colourless glass bottle.
(b) amber coloured bottle.
(c) tin container.
(d) aluminium container.

Answer: (b) amber coloured bottle.

1. Bromine is photosensitive and oxidizing, so it needs an amber bottle, and it attacks metals.

Teacher's Note:
a) Light and metals both affect bromine water.

17. Sameer observed stems of four plants in a nursery. They are sketched as A, B, C, D below. Of these the stem of the plant which conserves water is [0.5 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four sketches of plant stems: A a thorny stem with leaves, B a stem with two broad leaves, C a thorny woody stem, D a flat fleshy cactus stem with spines]

Answer: (d) D

1. A fleshy, spiny stem is a feature of a xerophyte.

Teacher's Note:
a) The cactus stem stores water and has spines in place of leaves.

18. Here are the pictures of cactus and lotus. You have observed their stems in the laboratory. The correct statement regarding the interior of the stems of these plants is: [0.5 Mark]
(a) The stem of lotus has no empty space inside.
(b) The stem of cactus is full of empty tubes.
(c) The interior of cactus stem is dry.
(d) The stem of lotus is hollow.

[Figure: Pictures of a cactus (a plant with flat spiny pads) and a lotus (a water plant with flowers and large round leaves floating above water)]

Answer: (d) The stem of lotus is hollow.

1. This is a comparison of the features of a hydrophyte and a xerophyte. The lotus stem has large air spaces and is hollow, while the cactus stem is fleshy and stores water.

Teacher's Note:
a) Hydrophytes have air cavities that help them float.

19. Observe the pictures of a bird and a bony fish. The feature that places them in the same phylum is [0.5 Mark]
(a) pointed heads.
(b) bulky thorax.
(c) presence of scales.
(d) post anal tails.

[Figure: Pictures of a pigeon (bird) and a bony fish with fins and scales]

Answer: (d) post anal tails.

1. Chordate characteristics include a post anal tail.

Teacher's Note:
a) Birds and bony fishes both belong to phylum Chordata.

20. An unlabelled outline diagram of an earthworm is drawn below. The important feature to be drawn and labelled for placing the earthworm in its phylum is [0.5 Mark]
(a) eye.
(b) clitellum.
(c) annuli.
(d) anus.

[Figure: An outline diagram of an earthworm with a dark band (clitellum) near the front end]

Answer: (c) annuli.

1. Annuli (ring-like segments) are the feature of phylum Annelida.

Teacher's Note:
a) The clitellum is a feature of the earthworm, but segmentation by annuli places it in Annelida.

SECTION - B

21. Take dilute sulphuric acid in a test tube and put a few zinc granules into the test tube. You would observe that [1 Mark]
(a) zinc granules change to powder.
(b) colour of zinc changes from grey to white.
(c) the size of the zinc granules keeps decreasing.
(d) the surface of zinc metal becomes bright.

Answer: (c) the size of the zinc granules keeps decreasing.

1. Zinc is consumed during the reaction.

Teacher's Note:
a) Zn + H₂SO₄ gives ZnSO₄ + H₂, so the zinc dissolves.

22. In the experiment shown a gas is evolved. Four groups of students have recorded their observations on the gas produced as shown in the following table. Choose the correct set of observations. Note that the positive responses are shown by '✓' and negative by 'X' signs respectively. [1 Mark]

[Figure: A test tube containing iron sulphide with dilute hydrochloric acid being added; a gas is evolved]

Answer: (b)

1. Hydrogen sulphide gas is produced, which is colourless, has a rotten egg smell and turns lead acetate paper black. This matches option (b).

Teacher's Note:
a) H₂S gives a black stain of lead sulphide on lead acetate paper.

23. In a simple pendulum experiment, students A, B and C varied the effective lengths of their pendulums as per the sequence shown in the table. The sequence followed by [1 Mark]
(a) students A and C are better than that of student B.
(b) students A and B are better than that of student C.
(c) students B and C are better than that of student A.
(d) students A, B and C are all equally good.

Answer: (a) students A and C are better than that of student B.

1. It is always a better experimental practice to take observations in a systematic sequential manner. A decreases the length in steps of 10 cm and C increases it in steps of 10 cm, while B is random.

Teacher's Note:
a) Vary the length steadily in one direction, not randomly.

24. Three students A, B and C determined the volume of a solid by immersing it in water in the overflow cans set up as shown. The result obtained will be wrong for [1 Mark]
(a) student A.
(b) student B.
(c) student C.
(d) all three students.

[Figure: Three overflow cans A, B and C with a spout and a measuring cylinder under it; picture not clear in the PDF - add image]

Answer: (d) all three students.

1. The overflow can must always be filled up to its spout before using it to measure the volume displaced by the immersed solid. The figure is not readable in the PDF, so the printed key is used.

Teacher's Note:
a) Fill the can to the spout, wait till the dripping stops, and only then immerse the solid.

25. The temperature-time variation graphs, as obtained by four students A, B, C and D are as shown. The graph, likely to be correct is that of student [1 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four graphs of temperature (30 to 80) against time (0 to 35): A starts with a rise and then falls and flattens; B falls, dips and rises again before falling; C falls in a step and then drops sharply near the end; D is a smooth curve that falls steeply at first and then flattens]

Answer: (d) D

1. The liquid cools faster first and slowly later on when its temperature gets close to the surrounding temperature.

Teacher's Note:
a) A smooth falling curve that flattens is the correct shape.

26. Diagrams of cells of an onion peel were labelled by four students as given below. The correctly labelled diagram is [1 Mark]
(a) A
(b) B
(c) C
(d) D

[Figure: Four onion peel cells labelled by students: A intercellular space, nucleus, protoplasm; B cell wall, nucleus, protoplasm; C cell wall, nucleus, cytoplasm, plasma membrane; D plasma membrane, nucleus, cytoplasm]

Answer: (c) C

1. This is the correct labelling: cell wall, nucleus, cytoplasm and plasma membrane.

Teacher's Note:
a) Label the cell wall, plasma membrane, cytoplasm and nucleus of a plant cell correctly.

27. Four slides were observed under the microscope for spot test as shown below. The correct identification of the four spots is [1 Mark]

[Figure: Four microscope slides A, B, C and D: A long cells with thick walls, B a layer of rectangular cells with nuclei, C a network of thick-walled cells, D scattered rounded cells; the images are dark in the PDF]

Answer: (d) A: sclerenchyma, B: onion peel, C: parenchyma, D: cheek cells

1. This is the correct identification of the four tissues.

Teacher's Note:
a) Use the shape and arrangement of cells to identify each tissue.

28. Paul was rushing with a bottle of tincture iodine. Some iodine solution splashed on his yellow coloured cotton shirt and also on the white table cloth. The stain on the table cloth was yellowish brown while that on his shirt was blue black. The most plausible scientific reason for this is that the [1 Mark]
(a) shirt was dyed with metanil yellow.
(b) shirt was starched after washing.
(c) table cloth was starched but not the shirt.
(d) shirt had absorbed sweat.

Answer: (b) shirt was starched after washing.

1. Iodine gives a blue black colour with starch, so the shirt must have been starched.

Teacher's Note:
a) The starch test is the reason for the blue black stain.

29. The teacher asked the students to correctly record results of the experiment done to detect presence of metanil yellow in the adulterated arhar dal (tuvar dal) sample that was provided to them. The correct recording of the experiment is done in table [1 Mark]
(a) A
(b) B
(c) C
(d) D

Answer: (b) B

1. Aqueous metanil yellow with HCl gives a pink colour, so the observation and inference in B are correctly recorded.

Teacher's Note:
a) Record the observation (what you see) and the inference (what it means) separately.

30. For collecting methane gas prepared in the laboratory, four students followed different procedures. The correct procedure was [1 Mark]
(a) gas jar half-filled with water was inverted on the beehive shelf.
(b) gas jar completely filled with water was inverted on the beehive shelf.
(c) an empty gas jar was inverted on the beehive shelf.
(d) an empty gas jar was placed with its bottom touching the beehive shelf.

Answer: (b) gas jar completely filled with water was inverted on the beehive shelf.

1. Methane gas is lighter than water and also insoluble in water, so it is collected by downward displacement of water in a jar completely filled with water.

Teacher's Note:
a) Fill the gas jar fully with water before inverting it over the beehive shelf.

SCORING KEY FOR SAMPLE PAPER III

QUESTIONWISE ANALYSIS FOR SAMPLE PAPER III

P: Procedural skills; M: Manipulative skills; O: Observational skills; D: Drawing skills; R: Reporting and interpretative skills