Class 6 Matter MCQ with Answers

Matter and Its States | NCERT - CBSE Curriculum

Practice Class 6 Matter MCQs.
Explore questions on solids, liquids, gases, molecular model, Brownian motion, diffusion, and surface tension for CBSE exams.

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Quick Revision: Matter and Its States

  • Definition: Matter is anything which occupies space and has mass.
  • Ancient Views: Maharishi Kanad proposed matter is made of anu and parmanu. Democritus called the smallest particle an atom (indivisible).
  • Modern View: Molecules are the smallest particles capable of independent existence. Atoms combine to form molecules.
  • Particle Characteristics: Particles of matter are (i) very small in size, (ii) have spaces between them, (iii) in constant random motion, (iv) attract each other.
  • Brownian Motion: Random zig-zag motion of particles due to collisions with surrounding molecules. Visible in dust particles in sunlight or pollen in water.
  • Cohesion: Force of attraction between molecules of the same substance. Adhesion: Force between molecules of different substances.
  • Surface Tension: Liquid surface tends to occupy minimum surface area due to cohesion. Causes spherical drops and allows insects to walk on water.
  • Three States: Solids (definite shape & volume), Liquids (definite volume, no shape), Gases (no definite shape or volume).
  • Fourth State — Plasma: Found at very high temperatures. Consists of positive ions and free electrons. Example: stars, lightning.
  • Change of State: Melting (solid→liquid), Boiling/Vaporisation (liquid→gas), Condensation (gas→liquid), Freezing (liquid→solid).
  • Solids: Strong inter-molecular forces, negligible inter-molecular space, molecules vibrate at fixed positions. Low thermal expansion. Exert pressure only downwards.
  • Liquids: Weaker forces than solids, molecules move within boundary. Have one free surface. Exert pressure in all directions. Show viscosity and surface tension.
  • Gases: Negligible inter-molecular forces, molecules far apart. Highly compressible. Exert pressure on walls via continuous collisions. Very fast diffusion.
  • Nanoparticles: A molecule or cluster of molecules at nanoscale (10⁻⁹ m).

Matter Class 6 Questions and Answers (FAQ)

What is matter and what are its four characteristics in Class 6 Science?
Matter is anything that occupies space and has mass. Its four main characteristics are: particles of matter are very small in size, they have spaces between them, they are in constant random motion, and they attract each other through cohesive and adhesive forces. These properties explain phenomena like Brownian motion, diffusion, and surface tension.
What are the three states of matter and their properties?
The three states of matter are: Solids have a definite shape and volume, strong intermolecular forces, and are rigid. Liquids have a definite volume but no definite shape, weaker forces than solids, and can flow. Gases have neither definite shape nor volume, negligible intermolecular forces, and are highly compressible. A fourth state called plasma exists at very high temperatures with ions and free electrons.
What is Brownian motion and why does it occur?
Brownian motion is the random zig-zag movement of tiny particles suspended in a fluid. It occurs because the particles of the surrounding medium (like air or water) are in constant random motion and continuously collide with the suspended particles. It can be observed when dust particles dance in a beam of sunlight entering a darkened room.
What is the difference between cohesion and adhesion?
Cohesion is the force of attraction between molecules of the same substance. Adhesion is the force of attraction between molecules of different substances. Water sticks to glass because adhesion (water-glass) is stronger than cohesion (water-water). Mercury does not stick to glass because cohesion (mercury-mercury) is stronger than adhesion (mercury-glass).
What is plasma and how is it different from gas?
Plasma is the fourth state of matter that exists at very high temperatures. Unlike gas, plasma consists of positive ions and free electrons. It is electrically conductive and responds to magnetic fields. Examples include stars (including the Sun), lightning, and fluorescent tube lights. Plasma is the most common state of matter in the universe.

Chapter Summary: Matter and Its States

Matter is defined as anything that occupies space and has mass. Ancient Indian philosopher Maharishi Kanad was the first to propose that matter is composed of tiny particles called anu and parmanu. Later, Greek thinker Democritus named the smallest indivisible particle the atom. Modern science confirms that molecules—clusters of atoms—are the smallest particles capable of independent existence.

Particles of matter exhibit four key characteristics: they are extremely small (about 10⁻¹⁰ m in diameter), have spaces between them (shown by the salt-dissolving experiment), are in constant random motion (Brownian motion), and attract each other through cohesive and adhesive forces. These inter-molecular forces determine the three primary states of matter: solids (strong forces, closely packed, definite shape), liquids (moderate forces, flow and take container shape), and gases (negligible forces, fill all available space). A fourth state, plasma, exists at extremely high temperatures and contains ions and free electrons. Understanding the molecular model helps explain everyday phenomena: why water forms spherical drops (surface tension), why mercury doesn't stick to glass (cohesion > adhesion), and why gases are compressible while solids are not.

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