NCERT Class 9 Science Is Matter Around Us Pure Questions

IS MATTER AROUND US PURE

1. Which of the following statements are true for pure substances?

(i) Pure substances contain only one kind of particles

(ii) Pure substances may be compounds or mixtures

(iii) Pure substances have the same composition throughout

(iv) Pure substances can be exemplified by all elements other than nickel

(a) (i) and (ii)

(b) (i) and (iii)

(c) (iii) and (iv)

(d) (ii) and (iii)

2. Rusting of an article made up of iron is called

(a) corrosion and it is a physical as well as chemical change

(b) dissolution and it is a physical change

(c) corrosion and it is a chemical change

(d) dissolution and it is a chemical change

3. A mixture of sulphur and carbon disulphide is

(a) heterogeneous and shows Tyndall effect

(b) homogeneous and shows Tyndall effect

(c) heterogeneous and does not show Tyndall effect

(d) homogeneous and does not show Tyndall effect

4. Tincture of iodine has antiseptic properties. This solution is made by dissolving

(a) iodine in potassium iodide

(b) iodine in vaseline

(c) iodine in water

(d) iodine in alcohol

5. Which of the following are homogeneous in nature?

(i) ice   (ii) wood    (iii) soil    (iv) air

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (i) and (iv)

(d) (iii) and (iv

6. Salt can be recovered from its solution by evaporation. Suggest some other technique for the same?

7. The ‘sea-water’ can be classified as a homogeneous as well as heterogeneous mixture. Comment.

8. While diluting a solution of salt in water, a student by mistake added acetone (boiling point 56°C). What technique can be employed to get back the acetone? Justify your choice.

9. What would you observe when

(a) a saturated solution of potassium chloride prepared at 60°C is allowed to cool to room temperature.

(b) an aqueous sugar solution is heated to dryness.

(c) a mixture of iron filings and sulphur powder is heated strongly.

10. Explain why particles of a colloidal solution do not settle down when left undisturbed, while in the case of a suspension they do.

11. Smoke and fog both are aerosols. In what way are they different?

12. Classify the following as physical or chemical properties

(a) The composition of a sample of steel is: 98% iron, 1.5% carbon and 0.5% other elements.

(b) Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.

(c) Metallic sodium is soft enough to be cut with a knife.

(d) Most metal oxides form alkalis on interacting with water.

Please refer to attached file for NCERT Class 9 Science Is Matter Around Us Pure Questions