Chemical And Physical Changes

Question 1

1

Answer 1

Q: What is a physical change?

Question 2

A: A change in appearance or state where no new substance is formed.

Question 3

Example: Melting ice, dissolving salt.

Answer 4

2

Question 5

A: A change that creates new substances with different properties.

Question 6

Example: Burning, rusting, neutralisation.

Answer 7

3

Question 8

A: They are rearranged but not changed chemically.

Answer 9

4

Question 10

A: Bonds between atoms are broken and new bonds form to make new substances.

Answer 11

5

Question 12

A: Physical — no new substance is formed.

Answer 13

6

Question 14

A: Physical — it changes state but remains H₂O.

Answer 15

7

Question 16

A: Chemical — it produces new substances like carbon dioxide and ash.

Answer 17

8

Question 18

A: It only changes state (liquid to gas), not the chemical identity.

Answer 19

9

Question 20

A: Yes — the food molecules are broken down and new substances are made.

Answer 21

10

Question 22

A: Yes — most physical changes are reversible.

Answer 23

11

Question 24

A: No — they often require another chemical reaction or are irreversible.

Answer 25

12

Question 26

A: Physical — it’s a state change (gas to liquid).

Answer 27

13

Question 28

A: Yes — a gas (CO₂) is produced and a new substance forms.

Answer 29

14

Question 30

A: Because no new substance is made and the salt can be recovered by evaporation.

Answer 31

15

Question 32

A: Temperature change, gas formation, colour change, or formation of a solid (precipitate).