CBSE Class 9 Science Chapter 05 Exploring Mixtures And Their Separation MCQs Set 02

Answer: (A) A saturated solution

Explanation:
Once the maximum amount of solute that can dissolve at that temperature has been added, the solution cannot hold any more solute and is called saturated.

Answer: (A) 5% m/m

Explanation:
Dividing the mass of turmeric by the total mass of the mixture and multiplying by 100 gives (8/160) x 100 = 5%.

Answer: (A) Gas particles move freely in every direction and mix uniformly with each other

Explanation:
Since gas particles are not confined and travel freely in all directions, two gases mixed together tend to blend evenly, giving a uniform composition throughout.

Answer: (A) They do not blend and instead settle into separate layers

Explanation:
Immiscible simply means the two liquids refuse to mix; instead of blending, they stay apart as distinct layers, as seen with oil floating over water.

Answer: (A) Crystallization

Explanation:
• Crystallization is the process by which particles arrange themselves into a regular geometric pattern.
• It occurs when a solute separates out of a saturated solution or vapour, forming crystals.
• Rock salt, mishri, and frost all form this way in nature.

Answer: (A) Seawater leads to a saturated solution, which then yields salt crystals

Explanation:
Seawater is first concentrated by evaporation until it becomes saturated with salt, and only then do salt crystals begin to separate out.

Answer: (A) A solution's concentration must be precise, since too little or too much solute can make it ineffective or even harmful

Explanation:
Both examples are used to show that solutions are not just about mixing substances freely — getting the right proportion of solute to solvent is essential for the solution to work as intended, whether for rehydration or crop protection.

Answer: (A) It separates blood components for disease diagnosis without needing electricity

Explanation:
Inspired by a spinning toy, the paperfuge performs centrifugation by hand, making it a low-cost way to separate blood samples for detecting diseases like malaria and anaemia in places without access to electric centrifuges.

Answer: (A) Sublimation

Explanation:
This direct solid-to-gas transition, occurring below the melting point, is called sublimation — the same behaviour shown by camphor in the chapter's activity.

Answer: (A) It acts as a coagulant, causing the milk proteins to clump together

Explanation:
The acid in lemon juice makes the milk proteins clump together, forming solid curds — this clumping action is what the chapter calls coagulation.

Answer: (A) Tiny droplets of oil are dispersed within water, which acts as the surrounding medium

Explanation:
In an oil-in-water emulsion, fine oil droplets stay spread out through water, with water forming the continuous background medium — unlike butter, which is the reverse, a water-in-oil emulsion.

Answer: (A) John Tyndall

Explanation:
The scattering of light by dispersed particles was first studied by the scientist John Tyndall, so it is called the Tyndall effect in his honour.

Answer: (A) The solute particles in a solution are too small to scatter light

Explanation:
Solution particles measure less than about 1 nanometre, far smaller than colloidal or suspended particles, so they are not large enough to scatter a passing beam of light.

Answer: (A) Distillate

Explanation:
The condensed, purified liquid gathered at the end of the distillation apparatus is referred to as the distillate.

Answer: (A) Each technique relies on a specific physical difference between the components, matched to the type of mixture being separated

Explanation:
Whether it is differences in solubility, boiling point, particle size, or density, the chapter repeatedly shows that a suitable separation method is picked based on the particular physical property that distinguishes the components of a given mixture.

Answer: (A) 12 g

Explanation:
Mass by mass percentage means grams of solute per 100 g of the mixture, so 4% of 300 g works out to (4/100) x 300 = 12 g of zinc oxide.

Answer: (A) 20% v/v

Explanation:
Two tablespoons give a total of 30 mL of concentrate. Using the v/v formula, (30 mL / 150 mL) x 100 gives 20%, meaning the concentrate makes up one-fifth of the total juice by volume.

Answer: (A) Solubility of the dissolved gas decreases as temperature rises, so it escapes more readily

Explanation:
Unlike solids, gases become less soluble in liquids as temperature increases. Warming the soda pushes dissolved carbon dioxide out of the solution faster, so the drink flattens sooner.

Answer: (A) The various components have boiling points that differ by less than 25 degrees Celsius

Explanation:
Simple distillation works well when boiling points differ by a wide margin, but petroleum fractions have closely spaced boiling points, under 25 degrees Celsius apart, so a more refined technique, fractional distillation, is needed to separate them cleanly.

Answer: (A) Residue

Explanation:
The chapter uses the term residue for the solid matter trapped on the filter paper during filtration, distinguishing it from the filtrate, which is the liquid that passes through.

Answer: (A) Petroleum gas, petrol, kerosene, diesel, bitumen

Explanation:
In the tower, lighter fractions with lower boiling points rise and are drawn off nearer the top, while heavier fractions with higher boiling points, like bitumen, settle and are collected lower down. The correct climb is petroleum gas, petrol, kerosene, diesel, then bitumen at the bottom.

Answer: (A) By simply evaporating seawater

Explanation:
Two traditional methods are described: panga salt came from boiling concentrated brine, while karkatch salt was produced by letting seawater evaporate naturally.
• This shows crystallization has been practised in India long before modern laboratory methods.
• Both methods rely on the same underlying principle of removing water to leave solid salt behind.

Answer: (A) Sedimentation, coagulation and filtration

Explanation:
The text explains that sewage treatment relies on sedimentation to let heavier particles settle, coagulation to clump fine particles together, and filtration to remove remaining solids, together producing water clean enough for reuse.

Answer: (A) Tiny droplets of water are spread through a continuous oil medium

Explanation:
An emulsion's name reflects which liquid is dispersed and which forms the surrounding medium. Since butter is water-in-oil, the water exists as fine droplets scattered within the oil, the opposite arrangement from milk, which is oil-in-water.

Answer: (A) It is stronger and more resistant to corrosion than iron alone

Explanation:
Alloys are generally made to improve on the properties of a single metal. Mixing iron with chromium, nickel and other elements at high temperature produces stainless steel, which resists rusting and is tougher than plain iron, and once formed, its components cannot be separated by ordinary physical methods.