Mixtures, solutions, suspensions, colloids, separation MCQs

Q1. Which of the following is NOT a characteristic of a true solution?

• A.It shows the Tyndall effect strongly
• B.Particles cannot be seen with the naked eye
• C.Particles do not settle on standing
• D.Particles pass through filter paper

Answer: A. It shows the Tyndall effect strongly

Concept involved: True solutions do NOT show the Tyndall effect because the solute particles (under 1 nm) are too small to scatter visible light. The other three properties are characteristic of true solutions. Putting it together the correct option is A) It shows the Tyndall effect strongly.

Q2. Which of the following is a homogeneous mixture?

• A.Sugar dissolved in water until completely clear
• B.Sand in water
• C.Oil and water shaken together
• D.Iron filings and sulphur powder

Answer: A. Sugar dissolved in water until completely clear

NCERT idea this hinges on: In a homogeneous mixture composition is uniform throughout and only one phase is visible. A clear sugar solution is uniform; the others have visible distinct phases (heterogeneous). Putting it together the correct option is A) Sugar dissolved in water until completely clear.

Q3. Which is the smallest particle size?

• A.Particles in a true solution (< 1 nm)
• B.Particles in a colloid (1-1000 nm)
• C.Particles in a suspension (> 1000 nm)
• D.Dust particles visible to the naked eye

Answer: A. Particles in a true solution (< 1 nm)

Key chapter idea: True solutions have the smallest particle size (under about 1 nm), colloids are intermediate, and suspensions have the largest particles. Hence true-solution particles are smallest. So the correct option is A) Particles in a true solution (< 1 nm).