Chapter - 1 Is Matter Around us Pure MCQs With Answer - Fully Solved

Chapter - 2 Is Matter Around us Pure

MCQs With Answer - Fully Solved

1. Which of the following statements is/are correct?

(a) All the constituent particles of a pure substance are the same in their chemical nature.

(b) A pure substance consists of a single type of particles.

(c) Most of the matter around us exist as mixtures of two or more pure components.

(d) All of these

Ans : (d) All of these

2. If the components of the substance can be separated by a chemical change only then it is a/an

(a) element

(b)  compound

(c)  mixture

(d) none of these

Ans :  compound

A compound can be separated into its components by chemical means while an element cannot be further separated. A mixture can be separated by physical means.

3. Identify the correct statement(s).

(a) Mixtures which have a uniform composition throughout are called homogeneous mixtures or solutions.

(b) A homogeneous mixture can have a variable composition.

(c) Heterogeneous mixtures have non-uniform compositions.

(d) All of these

Ans : (d) All of these

4. What type of mixtures are separated by crystallisation?

(a) A mixture in which one component is soluble in a solvent.

(b) A mixture in which impurities are soluble in a solvent.

(c) A mixture in which both the components are soluble in a solvent.

(d) A mixture in which both the components are insoluble in water.

Ans : (a) A mixture in which one component is soluble in a solvent.

Crystallisation is a process that separates a pure solid in the form of its crystals from a solution.

5. The zigzag movement of dispersed phase particle in a colloidal system is known as

(a) Brownian motion

(b) translational motion

(c) circular motion

(d) linear motion

Ans : (a) Brownian motion

The zigzag motion of colloidal particles is called Brownian motion.

6. A student mixed a small amount of iron filings and sulphur powder in a dish. He could not affect the separation by simple hand-picking. Which liquid will you suggest to affect the separation?

(a) Carbon disulphide

(b)  Cold water

(c)  Boiling water

(d) Kerosene

Ans : (a) Carbon disulphide

Sulphur is soluble in carbon disulphide while iron filings remain insoluble. Hence, the sulphur will  go into solution leaving behind iron filings.

7. The fine particles of an insoluble substance uniformly dispersed throughout a gas or liquid is called

(a) suspension

(b)  precipitate

(c) colloidal solution

(d) impurity

Ans : (c) colloidal solution

In colloidal solution, dispersed phase is dispersed uniformly in dispersion medium.

8. Substance P has the following properties:

1. Melts at 80cC

2. Boils at 150cC

3. Insoluble in water

Which method of separation would you use to obtain pure P from a mixture of P and water?

(a) Paper chromatography

(b) Fractional distillation

(c) Crystallisation

(d) Filtration

Ans : (d) Filtration

As substance P is insoluble in water, it can be separated by filtration.

9. What kind of solution is gel?

(a) Colloid

(b)  Mixture

(c)  Emulsion

(d) Suspension

Ans : (a) Colloid

Gel is a colloid in which liquid phase is dispersed in solid dispersion medium e.g. jelly, cheese, butter, etc.

10. Pigments of natural colours can be separated by

(a) chromatography

(b)  centrifugation

(c)  filtration

(d) sublimation

Ans : (a) chromatography

By chromatography technique, components of natural colours can be separated.

11. In ‘tincture of iodine’, a solute is_____________ and a solvent is .......... .

(a) alcohol, iodine

(b)  iodine, tin

(c)  iodine, alcohol

(d) tin, iodine

Ans : (c) iodine, alcohol

A solution of iodine in alcohol is known as ‘tincture of iodine’. It has iodine (solid) as the solute and alcohol (liquid) as the solvent.

12. Which of the following statements are correct about properties of colloids?

1. A colloid is a homogeneous mixture.

2. The size of particles of a colloid is too small to be individually seen by naked eye.

3. Colloids are big enough to scatter a beam of light passing through it and make its path visible.

(a)  1, 2 and 3

 (b) 2 and 3

(c)  1 and 2

(d) 1 and 3

Ans : (b)  2 and 3

Colloidal solutions are heterogeneous in nature.

13. The fine particles of an insoluble substance uniformly dispersed throughout a gas or liquid is called

(a) suspension

(b)  precipitate

(c) colloidal solution

(d) impurity

Ans : (c) colloidal solution

In colloidal solution dispersed phase is dispersed uniformly in dispersion medium.

14. Which of the following upon shaking with water will not form a true solution?

(a) Alum

(b)  Common salt

(c)  Albumin

(d) Sucrose

Ans : (c) Albumin

Albumin will form a colloidal solution since it is not soluble in water.

15. Which of the following will show Tyndall effect?

(a) Starch solution

(b) Sodium chloride solution

(c) Copper sulphate solution

(d) Sugar solution

Ans : (a) Starch solution

Starch solution will show Tyndall effect i.e. scattering of light since it is a colloidal solution.

16. An emulsion is a colloidal solution formed by mixing

(a) two miscible liquids

(b) any two liquids

(c) any two gases

(d) two immiscible liquids

Ans : (d) two immiscible liquids

Emulsion is a colloidal solution of two immiscible liquids mixed together e.g., milk.

17. When a beam of light is passed through a colloidal solution, it gets

(c)10-5 m - 10-7 m

(d) 107 - 109 m

(a) reflected

(b) absorbed

(c)  scattered

(d) refracted

Ans : (c) scattered

The scattering of beam of light on passing through colloidal solution is known as Tyndall effect.

18. Iodized common salt is

(a) homogeneous mixture

(b) heterogeneous mixture

(c) pure substance

(d) oxidized substance

Ans : (a) homogeneous mixture

Iodized common salt is a homogeneous mixture since the composition of iodine and salt is fixed throughout the iodized salt and there are no visible boundaries.

19. Pigments of natural colours can be separated by

(a) chromatography

(b)  centrifugation

(c)  filtration

(d) sublimation

Ans : (a) chromatography

By chromatography technique components of natural colours can be separated.

Ans : (a) 1-100 nm

The size of colloidal particles is in the range of 1 to 100 nm.

20. Brass contains

(a) gold and copper

(b)  copper and zinc

(c)  zinc and silver

(d) copper and silver

Ans :  copper and zinc

Brass is an alloy of copper and zinc.

21. Which of the following is a homogeneous mixture?

(a) Solution of sugar in water

(b) Chalk powder in water

(c) Kerosene oil in water

(d) None of these

Ans : (a) Solution  of  sugar  in  water Sugar solution is a homogeneous mixture.

22. Solutions with low concentrations of solutes are

(a) concentrated solutions

(b)  dilute solutions

(c)  solvents

(d) none of these

Ans :  dilute solutions

Solutions which contain small amount of solute are known as dilute solutions.

23. Which of the following statement is correct?

(a) A pure substance must contain only one type of atom.

(b) A mixture containing two compounds must be heterogeneous.

(c) A heterogeneous mixture must contain atleast three elements.

(d) A homogeneous mixture must be uniform.

Ans : (d) A homogeneous mixture must be uniform. The mixture which has a uniform composition throughout, is known as homogeneous mixture.

24. If we heat iodine, then it is a

(a) physical change

(b)  chemical change

(c)  no change

(d) colour change

Ans : (a) physical change

Iodine is converted into iodine vapours which can be condensed back to get iodine (solid).

25. Which of the following is not an example of a physical change?

(a) Dissolving sugar in water

(b) Casting iron in moulds

(c) Setting of cement

(d) Magnetisation of iron

Ans : (c) Setting of cement

Setting of cement is an example of permanent change which is irreversible, thence is not a physical change.

26. Smoke is an example of

(a) gas dispersed in liquid

(b) gas dispersed in solid

(c) solid dispersed in gas

 solid dispersed in solid

Ans : (c) solid dispersed in gas

In case of smoke solid particles are dispersed in gas.

27. Separation of petroleum into its components is done by

(a) chromatography

(b)  sublimation

(c)  distillation

(d) fractional distillation

Ans : (d) fractional distillation

Fractional distillation us used to separate components of petroleum.

28. Which one of the following is correctly matched?

(a) Emulsion - curd

(b)  Foam - mist

(c)  Aerosol - smoke

(d) Solid sol - cake

Ans : (c) Aerosol - smoke

Smoke is aerosol, solid dispersed in gas.

29. Iron rod turns red on heating. The change is a

(a) physical change

(b) permanent change

(c) physical and chemical change

(d) chemical change

Ans : (a) physical change

30. A mixture  contains  four  solid  compounds  A,  B,  C,D. On heating C changes to vapour state. C can be separated from rest of the solids by

(a) crystallisation

(b)  sublimation

(c)  distillation

(d) filtration

Ans :  sublimation

Sublimation technique of  purification  is  used  for those solids which are directly converted to gas phase without undergoing liquid phase.

31. Chemical changes are

(a) temporary, reversible and a new substance is produced

(b) always accompanied by exchange of light

(c) permanent, irreversible and a new substance is produced

(d) never accompanied by exchange of light and heat energy

Ans : (c) permanent, irreversible and a new substance is produced

32. Identify the false statement.

(a) Colloids are homogeneous

(b) Colloids show Tyndall effect

(c) Colloids show Brownian movement

(d) The size of colloidal particles ranges between 1-100 nm.

Ans : (a) Colloids are homogeneous

Colloids are heterogeneous in nature, made up of two different phases viz. dispersed phase and dispersion medium.

33. Select the incorrect statements(s).

1. Although ice, water and water vapour all look different and display different physical properties, they are chemically the same.

2. During burning of a candle, both physical and chemical changes take place.

3. Both water and cooking oil are liquid but their chemical characteristics are different. They differ in odour and inflammability.

4. It is the physical property of oil that makes it different from water.

(a) 1 and 2

(b) 2 and 3

(c)  1, 2 and 3

(d) Only 4

Ans : (d) Only 4

It is the chemical property of oil that makes it different from water.

34. Which gas present in air has the highest boiling point?

(a) Oxygen

(b)  Nitrogen

(c) Argon

(d) Hydrogen

Ans : (a) Oxygen

35. Which of the following are metalloid?

1.Boron

2.Sodium

3.Silicon

4.Chlorine

5.Germanium

(a)2 and 4

 (b) 1 and 4

(c) 3 and 5

(d) 1, 3 and 5

Ans : (d) 1, 3 and 5

Sodium is a metal while chlorine is a non-metal.

36. If the component of the substance can be separated by a chemical change only then it is

(a) element

(b)  compound

(c) mixture

(d) both (a) and 

Ans :  compound

A compound can be separated into its components by chemical means while an element cannot be further separated. A mixture can be separated by physical means.

37. Select the old one out.

(a) Carbon

(b)  Oxygen

(c) Iodine

(d) Mercury

Ans : (d) Mercury

Mercury is a metal while carbon, oxygen and iodine are non-metals.

38. An example of a chemical change is

(a) formation of clouds

(b) glowing of an electric light

(c) dropping sodium into water

(d) dissolving of salt in water

Ans : (c) dropping sodium into water

Formation of  clouds,  glowing  of  an  electric  light and dissolving of salt in water are the examples of a physical change.

39. Which of the following is not true for a compound?

(a) A compound is heterogeneous in nature

(b) A compound contains different elements in a fixed ratio.

(c) Properties of a compound are entirely different form those of the elements present in it.

(d) Constituents of a compound cannot be separated by simple physical methods.

Ans : (a) A compound is heterogeneous in nature

40. Which of the following involves both physical and chemical change?

(a) Burning of a candle

(b)  Rusting of iron

(c)  Cooking of food

(d) Boiling of water

Ans : (a) Burning of a candle

41. What is the name of the insoluble substance which settles to the bottom of its container?

(a) Solute

(b)  Solvent

(c) Sediment

(d) Slag

Ans : (c) Sediment

Sediment is the insoluble part of a mixture which settles down at the bottom of its container.

42. We can separate a pure solid from its solution by

(a) crystallization

(b)  simple distillation

(c) sedimentation

(d) both (a) and 

Ans : (a) crystallization

Only pure solid will be crystallised from its saturated solution.

43. Soda water is a solution of carbon-dioxide in water. What is this solution composed of?

(a) Liquid solute in a gaseous solvent

(b) Gaseous solute in a liquid solvent

(c) Liquid solute in a liquid solvent

(d) Gas in suspended form in liquid

Ans :  Gaseous solute in a liquid solvent Carbon-dioxide acts a solute in soda water.