Heterogeneous Mixtures MCQs Quiz | Class 9

Class IX Science (Code 086), Unit I: Matter – Its Nature and Behaviour. This quiz covers the definition, characteristics, and examples of heterogeneous mixtures. Attempt these 10 MCQs to test your understanding, review your score, and download the solution PDF for offline revision.

Understanding Heterogeneous Mixtures

A heterogeneous mixture is a type of mixture where the components are not uniformly distributed throughout the bulk. The different substances remain physically distinct, and there are visible boundaries of separation between them.

Key Characteristics

  • Non-Uniform Composition: The concentration of particles varies in different parts of the mixture.
  • Visible Boundaries: You can often see the different components with the naked eye or a simple microscope.
  • Variable Properties: Different parts of the mixture may exhibit different physical properties.
  • Particle Size: Generally, the particles are large enough to be seen (larger than 100 nm in suspensions).

Types of Heterogeneous Mixtures

There are two main categories often discussed in Class 9:

  1. Suspensions: A heterogeneous mixture containing solid particles large enough for sedimentation. Example: Sand in water.
  2. Colloids: These appear homogeneous but are actually heterogeneous under a microscope. Example: Milk, Fog.

Examples Table

Mixture Components Observation
Soil Sand, clay, pebbles, organic matter Visible distinct particles
Oil and Water Oil, Water Two distinct layers separate
Sulphur and Iron Filings Yellow powder, Grey metal Magnet can separate iron
Chalk Powder in Water Chalk, Water Particles settle at bottom

Summary for Revision

  • Heterogeneous mixtures are unstable; particles may settle over time (suspensions).
  • They can usually be separated by simple physical methods like filtration, hand-picking, or using a separating funnel.
  • The Tyndall effect (scattering of light) is observed in colloids and fine suspensions.

Extra Practice Questions

  1. Why is air usually considered homogeneous but sometimes heterogeneous? (Ans: Pure air is homogeneous; dusty/smoky air is heterogeneous).
  2. Name the technique to separate oil from water. (Ans: Separating Funnel).
  3. Is milk a homogeneous or heterogeneous mixture? (Ans: Heterogeneous – Colloid).
  4. What happens when a beam of light passes through a colloidal solution? (Ans: The path of light becomes visible due to the Tyndall effect).
  5. Can filtration separate the components of a colloid? (Ans: No, special techniques like centrifugation are needed).