SECTION - A
Q.1 Predict the maximum number of valence electrons possible for atoms in first period of periodic table.
Q.2 In a beetle population, the number of green beetles is more than blue and red beetles.
Give a reason behind this situation.
Q.3 Name the source of energy from which an ecosystem gets energy.
Q.4 Recycling is considered as a welcome practice to deal with the environmental problems. Justify this statement with two arguments.
Q.5 What is Chipko Movement ? Why should we conserve forest ?
Q.6 A converging lens has a focal length of 250 mm. Calculate its power and express it according to sign convention.
Q.7 For plants like banana and oranges that have lost their capacity to produce seeds a different ways are used for increasing their number. Explain the method used for such plants.
Q.8 Write structure of ethyl alcohol (ethanol) and identify its functional group. Give chemical equation of its reaction with
(i) sodium (ii) excess conc H2SO4 at 443 K
Q.9 The atomic number of Na and Mg is 11 and 12 respectively and they belong to the same period.
(a) Which one would have smaller atomic size ?
(b) Which one would be more electropositive ?
(c) To which group would each one belong ?
Q.10 Explain how the tendency to gain electron changes from left to right across the period.
Q.11 Atomic no. of an element is 16. Write its configuration give the number of valence electrons. Find valency.
Q.12 “Fossils are helpful in developing evolutionary relationships”.
(a) Give a suitable reason in support of this statement.
(b) The dominant trait masks the effect of recessive trait and there is expression of only one trait. Explain briefly.
Q.13 Explain any three methods that can be used for avoiding pregnancy.
Q.14 In an experiment, Mendel obtained 1014 plants, out of which 787 were having round seeds and 227 had wrinkled seeds in F2 generation :
(a) What was the approximate ratio obtained in F2 ?
(b) Under which law do you find this ratio ?
(c) Why is this law so called ?
Q.15 Variation is useful for the survival of species over time. But the variants have unequal chances of survival. Explain this statements
Q.16 Draw a neat diagram of eye and label on it – ciliary muscle, cornea, retina , iris.
Q.17 (a) Explain how are we able to see nearby as well as the distant objects clearly.
(b) Why a rainbow is seen in the sky only after rainfall ?
Q.18 It is desired to obtain an erect image of an object using a concave mirror of focal length 20 cm.
(i) Mention the range of distance of the object from the mirror for which this is possible.
(ii) Will the image thus obtained be bigger or smaller than the object ?
(iii) Draw a ray diagram to show the image formation in this case.
Q.19 Mineral riches of the crust are either extracted or used. For every ton of metal a large amount of slag is discarded which damages the environment. Explain the kind of management that we need in this regard. Give any two values attained from this management system.
Q.20 Write the general formula of alkane and alkyne. Draw the electron dot structure of ethene and ethyne and write their molecular formula with structural formula.
Q.21 (a) Identify the type of method of reproduction as used by unicellular organisms.
Define the identified method.
(b) How can the above method be classified further ?
(c) Differentiate between the process of reproduction as seen in Amoeba and Leishmania.
Q.22 (a) What is speciation ?
(b) What are the factors that lead to speciation ?
Please click the below link to access CBSE Class 10 Science Sample Paper 2019 Set B
