Chapter 2.  Is Matter Around us Pure

Class 9 Science Examplar Chapter 2 : IS MATTER AROUND US PURE Choose the correct answers :

Q1. Which of the following materials fall in the category of a ‘‘ Pure Substance ’’ ?

(A) Milk

(B) Air

(C) Wood

(D) Mercury

Ans : (D) Mercury

Q2. Which of the following will show ‘‘ Tyndall effect ’’ ?

(i) Salt solution

(ii) Milk

(iii) Copper sulphate solution .

(iv) Starch solution.

(A)  (i) and (ii) 

(B) (ii) and (iii)

(C)  (iii) and (iv)

(D) (ii) and (iv)

Ans : (D) (i) and (iv)

Q3. Which of the following are compounds ?

(A) Silicon

(B) Carbon-dioxide

(C) Soil

(D) Air

Ans : (B) Carbon-dioxide

Q4. Which of the following are chemical changes ?

(A) Mixing of iron filings and sand .

(B) Rusting of iron .

(C) Melting of butter in a palm .

(D) Dissolving common salt in Water .

Ans : (B) Rusting of iron .

Q5.  Fog , Clouds and mist are an example of :

(A) Foam

(B) Aerosol

(C) Emulsion

(D) Solid sol

Ans : (B) Aerosol

Q6. Which of the following is liquid-liquid solution ?

(A) Emulsion

(B) Gel

(C) Foam

(D) Solid sol

Ans : (A) Emulsion

Q7. Which of the following statements are true for pure substances ?

(i) Pure substances contain only one kind of particles .

(ii) Pure substance 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)

Ans : (B) (i) and (iii)

Q8. 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 chemical change .

(D) dissolution and it is a chemical change .

Ans : (C) corrosion and it is chemical change .

Q9.  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 shows Tyndall effect .

(D) Homogeneous and  does not shows Tyndall effect .

Ans : (D) Homogeneous and  does not shows Tyndall effect .

Q10. 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

Ans : (D) iodine in alcohol . [A solution of iodine in alcohol known as tincture of iodine, has iodine as the solute and alcohol as the solvent .]

Q11. 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)

Ans : (C) (i) and (iv)

Q12. Which of the following are physical changes ?

(i) Melting of iron metal .

(ii) Rusting of iron .

(iii) Bending of an iron rod .

(iv) Drawing a wire of iron metal .

(A) (i) , (ii) and (iii)

(B) (i) , (ii) and (iv)

(C) (i) , (iii) and (iv)

(D) (ii) , (iii) and (iv)

Ans : (C) (i) , (iii) and (iv)

Q13. Which of the following are chemical changes ?

(i) Decaying of wood

(ii) Burning of wood

(iii) Sawing of wood

(iv) Hammering of a nail into a piece of wood

(A) (i) and (ii)

(B) (ii) and (iii)

(C) (iii) and (iv)

(D) (i) and (iv)

Ans : (A) (i) and (ii)

Q14. Two substances, A and B were made to react to form a third substance,  according to the following reaction  . Which of the following statements concerning this reaction are incorrect ?

(i) The product  shows the properties of substances A and B .

(ii) The Product will always have a  fixed composition .

(iii) The product so formed cannot be classified as a compound .

(iv) The product so formed is an element .

(A)  (i) , (ii) and (iii)

(B) (ii) , (iii) and (iv)

(C) (i) , (iii) and (iv)

(D) (ii) , (iii) and (iv)

Ans : (C) (i) , (iii) and (iv)

Q15. Two chemical species X and Y combine together to form a product P which contains both X and Y 

 X and Y cannot be broken down into simpler substances by simple chemical reactions . Which of the following concerning the species X , Y and P are correct ?

(i) P is a compound .

(ii) X and Y are compounds .

(iii) X and Y are elements .

(iv) P has a fixed composition

(A) (i) , (ii) and (iii)

(B) (i) , (ii) and (iv)

(C) (ii) , (iii) and (iv)

(D) (i) , (iii) and (iv)

Ans : (D) (i) , (iii) and (iv)

Q16. Which of the following are not compounds ?

(A) Potassium chloride

(B) Carbon monoxide

(C) Aluminium

(D) Iron sulphide

Ans : (C) Aluminium .

Q17. Which of the following element is called metalloids ?

(A) Boron

(B) Sodium

(C) Potassium

(D) Oxygen

Ans : (A) Boron

Q18. Which of the following element is called metal ?

(A) Silicon

(B) carbon

(C) oxygen

(D) gold

Ans : (D) gold

Q19. Which of the following element is called non-metals ?

(A) Silver

(B) copper

(C) iron

(D) carbon

Ans : (D) carbon

Q20. Which of the following metal is liquid at room temperature ?

(A) Copper

(B) Sodium

(C) Mercury

(D) Bromine

Ans : (C) Mercury

Q21. Which of the following  statement is correct ?

(i) Metals have a lustre .

(ii) Non-metals are lustrous , sonorous or malleable .

(iii) Metals are good conductors of heat and electricity .

(iv) Metals are ductile .

(A)  (i) , (ii) and (iii)

(B) (ii) , (iii) and (iv)

(C) (i) , (ii) and (iv)

(D) (i) , (iii) and (iv)

Ans :  (D) (i) , (iii) and (iv) .

Q22. The component of the solution that dissolves the other component ,then it is called :

(A) Solvent

(B) Solute

(C) Solution

(D) Both (A) and (B)

Ans : (A) Solvent .

Q23.  Is the technique used for separation of those solutes that dissolve in the same solvent .

(A) Sublimation .

(B) Chromatography .

(C) Fractional distillation .

(D) Crystallisation .

Ans : (B) Chromatography .

Class 9 Science Examplar Chapter 2 :  IS MATTER AROUND US PURE Fill in the blanks :

Q24. A colloid is a  mixture and its components can be separated by the technique known as  .

Ans :  Heterogeneous , centrifugation .

Q25. Ice, water and water vapour look different and display different  properties but they are  the same .

Ans : physical , chemically

Q26. A mixture of chloroform and water taken in a separating funnel is mixed and left undisturbed for some time . The upper layer in the separating funnel will be of  and the lower layer will be that of  .

Ans :  water , chloroform .

Q27. A mixture of two or more miscible liquids, for which the difference in the boiling points is less than 25K can be separated by the process called  .

Ans : Fractional distillation .

Q28. When light is passed through water containing a few drops of milk, it shows a bluish tinge . This is due to the  of light by milk and the phenomenon is called  . This indicates that milk is a  solution .

Ans : scattering , Tyndal effect , colloidal .

Q29. Suspension is a  mixture .

Ans : heterogeneous .

Q30. A solution is a  mixture .

Ans : homogeneous .