Mastering Matter: Subjective Questions & Exemplar Problems for Class 6

Overview Subjective Q&A Exemplar Q&A Comments

States of Matter – Study Guide

Overview of States of Matter

Matter is anything that has mass and occupies space. The physical state of matter depends on its particle arrangement, energy, and bonding forces. The three main states of matter are:

• Solids – Have fixed shape and volume.
• Liquids – Have fixed volume but no fixed shape.
• Gases – Neither fixed shape nor fixed volume.

Each state of matter behaves differently based on its properties like intermolecular forces, density, and kinetic energy.

Subjective Questions

Comparison Questions

1. Compare the properties of solids, liquids, and gases.

The three states of matter differ significantly based on particle behavior, shape, and volume.

Property	Solid	Liquid	Gas
Shape	Fixed	Takes shape of container	Takes shape of container
Volume	Fixed	Fixed	Not fixed
Force of Attraction	Very strong	Moderate	Very weak
Movement of Particles	Vibrate in fixed positions	Move freely, less than gases	Move rapidly in all directions

Conceptual Understanding

2. Why are liquids and gases called fluids?

Liquids and gases are called fluids because they can flow. Their particles are not held in fixed positions and can move freely, allowing them to take the shape of the container.

3. What are atoms and molecules? Give examples.

Atoms are the basic building blocks of matter, e.g., Hydrogen (H).
Molecules consist of two or more atoms chemically bonded, e.g., Water (H₂O).

Differences and Classification

4. Differentiate between elements and compounds.

Elements consist of only one kind of atom, while compounds consist of two or more different types of atoms chemically bonded.

Basis	Elements	Compounds
Composition	One kind of atom	Two or more different atoms
Separation	Cannot be broken down	Can be broken into simpler substances
Example	Oxygen (O), Hydrogen (H)	Water (H₂O), Carbon dioxide (CO₂)

5. Order solid, liquid, and gas based on forces and spaces.

• Increasing intermolecular forces: Gas < Liquid < Solid
• Decreasing intermolecular spaces: Gas > Liquid > Solid

Exemplar Problems

1. Is a spring a solid even though it changes shape?

Yes. A spring returns to its original shape after stretching, showing elasticity. This is a characteristic of solids, confirming that spring is a solid.

2. Why do gases fill the container they are kept in?

Due to weak intermolecular forces and high kinetic energy, gas particles move freely and spread to occupy all available space.

3. What are the necessary conditions to classify matter?

Anything that has mass and occupies space is matter. Since forces have neither, they are not classified as matter.

4. In which state is water least dense?

Water is least dense in its gaseous state (steam) because particles are far apart and occupy more volume.

5. Name a unique property of liquids not seen in solids.

Liquids can flow and adapt to the shape of the container, unlike solids which retain their shape.