The following 20 Multiple Choice Questions (MCQ) are based on
Chapter 5: Exploring Mixtures and their Separation from the NCERT Class 9
Science textbook Exploration. Each question has four options - select the
best answer and click to check.
Instructions: Read each question carefully. Choose the most
appropriate option from (a), (b), (c), or (d). Click
Show Answer to reveal the correct answer with explanation.
Multiple Choice Questions
1Which is a homogeneous mixture?
(a) Sand in water
(b) Sugar dissolved in water
(c) Chalk powder in water
(d) Oil and water
(b) is correct
A sugar solution has uniform composition throughout.
2Which is a heterogeneous mixture?
(a) Vinegar
(b) Air
(c) Sand and water
(d) Salt solution
(c) is correct
Its composition is non-uniform, and the sand can be seen and settles on standing.
3A solution consists of:
(a) A solute and a solvent
(b) Only a solvent
(c) Only solids
(d) Two immiscible liquids only
(a) is correct
The solute dissolves in the solvent to form a homogeneous mixture.
4In a sugar-water solution, water is usually the:
(a) Solute
(b) Solvent
(c) Residue
(d) Sublimate
(b) is correct
Water is the component that dissolves the sugar.
5Mass percentage of a solution is:
(a) Mass of solute / mass of solution x 100
(b) Mass of solvent / volume of solution
(c) Volume of solute / mass of solvent
(d) Mass of solution / mass of solute
(a) is correct
Mass by mass percentage compares solute mass with total solution mass.
6Ten grams of salt dissolved in 90 g water gives a mass percentage of:
(a) 9%
(b) 10%
(c) 11.1%
(d) 90%
(b) is correct
The solution mass is 100 g, so (10/100) x 100 = 10%.
7A solution that cannot dissolve more solute at a given temperature is:
(a) Dilute
(b) Unsaturated
(c) Saturated
(d) Heterogeneous
(c) is correct
It has reached its solubility limit at that temperature.
8Solubility means the maximum amount of solute that:
(a) Evaporates at any temperature
(b) Dissolves in a given amount of solvent at a specified temperature
(c) Settles immediately
(d) Passes through filter paper
(b) is correct
Solubility must be stated for a particular solvent quantity and temperature.
9Which method is best for obtaining pure crystals from an impure solid solution?
(a) Crystallisation
(b) Handpicking
(c) Sedimentation
(d) Magnetic separation
(a) is correct
Crystallisation separates a dissolved solid as well-formed, relatively pure crystals.
10Why is crystallisation often preferred to complete evaporation?
(a) It always needs no heat
(b) It can yield purer solid without strong heating to dryness
(c) It separates immiscible liquids
(d) It removes only large particles
(b) is correct
Controlled crystallisation excludes many impurities and avoids possible decomposition on intense heating.
11Distillation separates components mainly using differences in:
(a) Colour
(b) Boiling point
(c) Particle shape
(d) Magnetism
(b) is correct
A more volatile component vaporises and is then condensed separately.
12What is the role of a condenser in distillation?
(a) To heat the mixture
(b) To cool vapour into liquid
(c) To filter a suspension
(d) To form a precipitate
(b) is correct
The condenser removes heat from vapour so it becomes liquid distillate.
13Paper chromatography can separate:
(a) Different pigments in ink
(b) Stones from rice
(c) Oil from water using a tap
(d) Iron filings from sand
(a) is correct
Components move at different rates on paper because of differing affinities for the solvent and paper.
14Which apparatus is suitable for separating mustard oil and water?
(a) Separating funnel
(b) Evaporating dish
(c) Filter paper only
(d) Chromatography paper
(a) is correct
Immiscible liquids form layers and can be drained separately through a separating funnel.
15Which substance can be separated from a mixture by sublimation?
(a) Common salt
(b) Sand
(c) Naphthalene
(d) Sugar solution
(c) is correct
Naphthalene changes directly from solid to vapour on heating and deposits again on cooling.
16Which property is typical of a suspension?
(a) Particles never settle
(b) Particles settle on standing and can be filtered
(c) It is always transparent
(d) It is homogeneous
(b) is correct
Suspension particles are large enough to settle and be retained by ordinary filtration.
17Which property distinguishes many colloids from true solutions?
(a) They always settle rapidly
(b) They scatter a beam of light
(c) They contain no dispersed particles
(d) They are always colourless
(b) is correct
Colloidal particles scatter light, producing the Tyndall effect.
18Milk is best classified as a:
(a) True solution
(b) Colloid
(c) Pure substance
(d) Suspension that settles quickly
(b) is correct
Tiny droplets are dispersed through water and do not settle readily.
19The visible path of light through a colloid is called:
(a) Sublimation
(b) Tyndall effect
(c) Crystallisation
(d) Decantation
(b) is correct
Scattering by colloidal particles makes the light beam visible.
20Which sequence can separate sand, salt and naphthalene?
(a) Filter, magnet, distil
(b) Sublime naphthalene, dissolve salt in water, filter sand, then evaporate or crystallise
(c) Chromatograph, decant, freeze
(d) Use only a separating funnel
(b) is correct
Sublimation removes naphthalene; water dissolves salt, filtration removes sand, and crystallisation recovers salt.
