CBSE Class 9 Chemistry Is Matter Around Us Pure Worksheet Set C

Read and download free pdf of CBSE Class 9 Chemistry Is Matter Around Us Pure Worksheet Set C. Students and teachers of Class 9 Chemistry can get free printable Worksheets for Class 9 Chemistry in PDF format prepared as per the latest syllabus and examination pattern in your schools. Standard 9 students should practice questions and answers given here for Chemistry in Grade 9 which will help them to improve your knowledge of all important chapters and its topics. Students should also download free pdf of Class 9 Chemistry Worksheets prepared by school teachers as per the latest NCERT, CBSE, KVS books and syllabus issued this academic year and solve important problems provided here with solutions on daily basis to get more score in school exams and tests

Is Matter Around Us Pure Class 9 Chemistry Worksheet Pdf

Class 9 Chemistry students should refer to the following printable worksheet in Pdf for Is Matter Around Us Pure in standard 9. This test paper with questions and answers for Grade 9 Chemistry will be very useful for exams and help you to score good marks

Class 9 Chemistry Worksheet for Is Matter Around Us Pure

 

Very Short Answer Type Question

Question. Name the process by which all dyes present in black ink be recovered.
Answer :
 Chromatography.

Question. How can you test the purity of a given substance?
Answer :
 A pure substance always has the same taste, colour or texture at particular temperature and pressure and fixed melting or boiling point. For example : Pure water boils at 100°C but if it has some impurities then water boils at a temperature above 100°C.

Question. What is decantation? Explain.
Answer :
 Decantation is the process of separating insoluble solids from liquids. A suspension of solid particles in a liquid is allowed to stand for sometime. Insoluble solid particles settle down at the bottom due to their weight. This is called sedimentation. The clear liquid is then transferred into another container, without disturbing the settled particles. In other words, clear liquid is decanted and separated from solid.

Question. Hydrogen is considered as element. Why?
Answer :
 Hydrogen have one type of element and it cannot be broken by physical or chemical process, so it is considered as element.

Question. Classify the elements.
Answer :
 (1) Metals, (2) Non-metals, and (3) Metalloids.

Question. Give an example of a liquid and liquid type solution.
Answer :
 Vinegar is a mixture of acetic acid and water.

Question. A system which have same properties throughout is called-
Answer :
 Homogeneous.

Short / Long Answer Type Question

Question : Classify each of the following as a homogeneous or heterogeneous mixture. Soda water, wood, air, soil, vinegar, filtered tea.
Answer :
 Homogeneous mixtures: Air, soda water, vinegar, filtered tea.
Heterogeneous mixtures: Wood, soil,

Question : Which of the following materials fall in the category of a "pure substance"?
(a) Ice (b) Milk (c) Iron
(d) Hydrochloric acid (e) Calcium oxide (f) Mercury
(g) Brick (h)Wood (i) Air
Answer :
 Ice, iron, calcium oxide, mercury are pure substance as they have definite composition.
Milk is a colloid, so it is a heterogeneous mixture.
Hydrochloric acid is also a mixture of hydrogen chloride gas and water.

Question : Which of the following will show "Tyndall effect"?
(a) Salt solution
(b) Milk
(c) Copper sulphate solution
(d) Starch solution
Answer :
 Milk and starch solution will show "Tyndall effect" as both of these are colloids.

Question : Which of the following are chemical changes?
(a) Growth of a plant
(b) Rusting of iron
(c) Mixing of iron filings and sand
(d) Cooking of food
(e) Digestion of food
(f) Freezing of water
(g) Burning of a candle
Answer : Growth of a plant, rusting of iron, cooking of food, digestion of food, burning of a candle are chemical changes, because here the chemical composition of substance changes.

Question : How will you separate a mixture containing kerosene and petrol (difference in their boiling points is more than 25°C), which are miscible with each other?
Answer : 
Simple distillation is the method which can separate the mixture of kerosene and petrol (b.p. differ by more than 25°C).
Method:In a distillation flask, a mixture of kerosene and petrol is taken as shown in figure. The mixture is heated slowly and the temperature is recorded with the help of thermometer. Petrol (b.p. = 70° C to 1200 ° C) vaporizes first and the temperature becomes constant for some time (till all petrol evaporates from the mixture).
Vapours of petrol are condensed and collected in another container while the kerosene remains in the distillation flask. As soon as the temperature starts’ rising again, the heating is stopped and both the components are collected separately.

Question : What types of mixtures are separated by the technique of crystallisation?
Answer :
 Crystallisation method can be used for the purification of those mixtures which Contain insoluble and/or soluble impurities.
Have crystalline nature.
Cannot be separated by filtration as some impurities are soluble.

Question : Try segregating the things around you as pure substances or mixtures.
(a) Wood
(b) Coal
(c) Milk
(d) Sugar
(e) Common salt
(f) Soap
(g) Soil
(h) Rubber
Answer :
(a) Mixture
(b) Mixture
(c) Mixture
(d) Pure substance
(e) Pure substance
(f) Compound/mixture
(g) Mixture
(h) Pure substance

Question : Which separation techniques will you apply for the separation of the following?
(a) Sodium chloride from its solution in water.
(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride.
(c) Small pieces of metal in the engine oil of a car.
(d) Different pigments from an extract of flower petals.
(e) Butter from curd.
(f) Oil from water.
(g) Tea leaves from tea.
(h) Iron pins from sand.
(i) Wheat grains from husk.
(j) Fine mud particles suspended in water.
Answer :
(a) Evaporation
(b) Sublimation
(c) Filtration
(d) Chromatography.
(e) centrifugal machine or churning the curd by hand.
(f) Decantation
(g) Filtration.
(h) Magnetic Separation.
(i) Winnowing.
(j) Coagulation and decantation:

Question : Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution).
(a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K?
(b) Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools?
Explain.
(c) Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature?
(d) What is the effect of change of temperature on the solubility of a salt?
Answer :

(a) Mass of potassium nitrate needed to produce its saturated solution in 100 g of water at 313 K = 62 g
Mass of potassium nitrate needed to produce its saturated solution in 50 g of water at 313
K = 62/100 x 50g = 31g
(b) Crystals of potassium chloride are formed. This happens as solubility of solid decreases with decreasing the temperature.
(c) Solubility of each salt at 293 K
Potassium nitrate 32 g per 100 g water
Sodium chloride 36 g per 100 g water
Potassium chloride 35 g per 100 g water
Ammonium chloride 37 g per 100 g water
Note:Solubility of a solid is that amount in gram which can be dissolved in 100 g of water (solvent) to make saturated solution at a particular temperature.
Ammonium chloride has the maximum solubility (37 g per 100 g of water) at 293 K.
(d) Solubility of a (solid) salt decreases with decrease in temperature while it increases with rise in temperature.

 

1. What are mixtures? Give examples.

2. What are pure substances?

3. Why do we call sugar a pure substance?

4. What are saturated and unsaturated solutions?

5. Define a solution.

6. What is a suspension? Give its example and properties.

7. Define concentration of a solution.

8. What is Tyndall effect?

9. What is the difference between True solution and colloids?

10. What are alloys? Why are alloys called as mixture?

11. Write the characteristics of brass.

12. Define solute and solvent.

13. What is solubility?

14. Give properties of a true solution.

15. Why do we need to separate mixtures?

16. How can we separate cream from milk?

17. Write the applications of centrifugation.

18. How can we separate a mixture of salt and ammonium chloride? Draw a diagram.

19. What is chromatography? Explain the process.

20. How can you separate copper sulphate from an impure sample?

21. What types of mixture are separated by fractional distillation process? Draw a diagram.

22. Draw a diagram to explain the process of separating acetone and water.

23. Explain with the diagram the method of separating kerosene oil from water by using a separating funnel.

24. What are physical and chemical changes?

25. Write difference between mixtures and compounds.

26. Give definitions of elements and compounds.

27. What are metals and non-metals?

28. If 110g of salt is present in 550 g of solution, calculate the concentration.

29. What is the concentration of a solution which contains 16 g of urea in 120 g of solutions?

30. How much water should be added to 15 g of salt to obtain 15% salt solution?

31. A solution contains 5.6 ml of alcohol mixed with 76 ml of water. Calculate the concentration of the solution.

32. How much water should be added to 12 ml of alcohol to obtain 12% alcohol solution?

33. If 25 ml of acetone is present in 150 ml of its aqueous solution, calculate the concentration.

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