Colloids vs Suspensions vs True Solutions MCQs Quiz | Class 9

This quiz for Class IX Science (Code 086), Unit I: Matter – Its Nature and Behaviour covers the distinctions between True Solutions, Colloids, and Suspensions. It focuses on properties such as transparency, filtration, and stability based on practical criteria. Test your understanding, view your score, and download the solution PDF for revision.

Understanding Mixtures: Solutions, Suspensions, and Colloids

In Class 9 Science, Unit I, we classify mixtures based on particle size and properties. The three main types are True Solutions, Suspensions, and Colloids.

1. True Solutions

A true solution is a homogeneous mixture of two or more substances. The particles are extremely small (less than 1 nanometer in diameter) and cannot be seen even with a microscope.

  • Transparency: Transparent. Light passes through easily without scattering.
  • Filtration: Particles pass through filter paper.
  • Stability: Stable; particles do not settle down upon standing.
  • Example: Salt in water, sugar in water.

2. Suspensions

A suspension is a heterogeneous mixture containing solid particles large enough for sedimentation.

  • Transparency: Opaque or cloudy. They block light or scatter it heavily.
  • Filtration: Particles do not pass through filter paper; they leave a residue.
  • Stability: Unstable; particles settle down when left undisturbed.
  • Example: Muddy water, chalk powder in water.

3. Colloids (Colloidal Solutions)

A colloid is a mixture where particle size is intermediate between a true solution and a suspension (1 to 100 nanometers). They appear homogeneous but are actually heterogeneous.

  • Transparency: Translucent. They scatter a beam of light passing through them (Tyndall Effect).
  • Filtration: Particles pass through ordinary filter paper.
  • Stability: Stable; particles do not settle down.
  • Example: Milk, fog, starch solution.

Comparison Summary

Property True Solution Colloid Suspension
Type Homogeneous Heterogeneous Heterogeneous
Particle Size Very small (<1 nm) Medium (1-100 nm) Large (>100 nm)
Tyndall Effect No Yes Sometimes (until settled)
Stability Stable Stable Unstable

Quick Revision Points

  • Tyndall Effect: The scattering of light by colloidal particles makes the path of light visible.
  • Filtration Criteria: Only suspensions can be separated by filtration because their particles are larger than the pores of filter paper.
  • Stability Test: Leave the mixture undisturbed. If particles sink to the bottom, it is a suspension.