Answer key

Prepared by: learnloophq@gmail.com

Last edited 25 days ago by Learn LoopHQ.

Chapter: 02. Matter

⁠

Section A: Multiple Choice Questions

c) Plastic

c) Mass

a) Solid

c) Brownian motion

d) Sublimation

Section B: Fill in the Blanks

matter

volume

cohesive

volume

freezing

Section C: True or False

False

True

False

True

False

Section D: Short Answer Questions

Two common properties of all matter are that they have mass and they occupy space.

An atom is the smallest particle that doesn’t have an independent existence, while a molecule is the smallest particle that does have an independent existence.

The three main states of matter are solid, liquid, and gas.

Solids do not flow because the strong intermolecular forces of attraction hold their molecules in fixed positions, preventing them from moving freely.

A chemical change is a type of transformation where a new substance is formed, and its properties are entirely different from the original substance.

Section E: Diagram-Based Question

a) C b) A c) C

Section F: Identifying and Differentiating Concepts

Boiling is the process where a liquid changes into vapor at a fixed temperature (its boiling point), and it occurs throughout the liquid. Evaporation is the process where a liquid changes into vapor at any temperature below its boiling point, and it occurs only from the surface of the liquid.

Natural matter is found in nature (e.g., rock, water, air), while human-made matter is produced by humans (e.g., plastic, steel, glass).

Section G: Observation-Based Questions

The observation that proved water has mass was that the pan of the beam balance with the glass containing water moved downwards, indicating the water’s weight.

Water did not enter the inverted glass initially because the glass was already filled with air, which occupies space and prevented the water from entering.

Section H: Long Answer Questions

Solids have a definite shape and volume because their molecules are packed very closely together with negligible space between them, and the intermolecular forces are very strong, holding the molecules in fixed positions. They can only vibrate, not move around. Liquids, however, have a definite volume because their molecules are still held together, occupying a specific amount of space. But, they have no definite shape because the intermolecular forces are weaker than in solids, allowing molecules to move freely within the liquid’s boundaries and take the shape of any container they are in.

Water can exist as ice (solid), water (liquid), and steam (gas). The interconversion occurs as follows: When ice is heated, it undergoes melting and changes into water. If water is heated further, it undergoes boiling and changes into steam. Conversely, when steam is cooled, it undergoes condensation and changes back into water. If water is cooled further, it undergoes freezing and changes back into ice. These processes show how water changes states depending on temperature.

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