Chemical & Physical changes

Question 1

Physical and Chemical changes occur because of which interactions?

Answer 1

Matter & electricity
Matter & light
Matter & heat
Mixing

Question 2

What is an exothermic reaction?

Answer 2

Reaction that gives out heat

Question 3

What are examples of chemical changes in exothermic reactions?

Answer 3

Oxidation
Rusting
Corrosion

Question 4

What are examples physical changes in Exothermic reactions?

Answer 4

Condensation

Freezing

Question 5

What is an Endothermic Reaction?

Answer 5

Reaction that absorbs heat from surroundings

Question 6

What are examples of chemical changes in Endothermic reaction?

Answer 6

Photosynthesis

Photography

Question 7

What are examples of physical changes in Endothermic reaction?

Answer 7

Evaporation

Melting

Question 8

What are reactions that involve interactions between matter and heat?

Answer 8

Oxidation
Combustion
Thermal Decomposition

Question 9

Is respiration an example of oxidation?

Answer 9

Yes, as you respire, oxygen reacts with glucose to produce Carbon dioxide, water and energy

Question 10

What are the chemical reactions that involve matter and light?

Answer 10

Photography

Photosynthesis

Question 11

What are chemical reactions that involve matter and electricity?

Answer 11

Electrosis

Question 12

What are the processes called inelectrosis?

Answer 12

Electropltiny

Refining of metals

Question 13

What are the 3 reactions for mixing?

Answer 13

metal + acid = hydrogen + salt
Carbonate + acid = carbon dioxide + salt + water
acid + alkali = salt + water

Question 14

What substance has PH level of 7?

Answer 14

Distilled water

Question 15

When calcium carbonate mix with hydrochloric acid, what is produced?

Answer 15

carbon dioxide + calcium chloride

Question 16

How do you test if carbon dioxide is produced?

Answer 16

Add limewater, if the limewater turns chalky, then there is presence of carbon dioxide

Question 17

What are examples of neutralization?

Answer 17

Sodium hydroxide + sodium hydochloride

Question 18

What is a source for sulphur dioxide?

Answer 18

Acid rain

Burning of fuel

Question 19

What are chemical reactions that bring harm to our environment?

Answer 19

Rusting
Burning
Food Decay

Question 20

What are examples of indicators?

Answer 20

Universal indicator

red and blue litmus paper

Question 21

What turns Blue litmus red?

Answer 21

acid

Question 22

What happens to the blue litmus paper when it comes into contact with sodium hydroxide?

Answer 22

It will remain blue

Question 23

What PH value does green represent

Answer 23

neutral (7)

Question 24

Are acid and alkaline conductors of electricity?

Answer 24

Yes

Question 25

What are examples of acid?

Answer 25

Hydochloride acid Sodium Chloride Calcium Chloride

Question 26

What are examples of alkali?

Answer 26

Sodium hydroxide Calcium hydroxide Magnesium hydroxide

Question 27

The number of reactant atoms equivalent to the number of atoms of products because?

Answer 27

Extra atoms cannot be created or destroyed in chemical reactions

Question 28

What are benefits of chemical reactions in nature?

Answer 28

Photosynthesis Respiration Food Decay

Question 29

What are the benefits of chemical reactions in farming?

Answer 29

Food decay | Pesticide

Question 30

What are the benefits of chemical reactions in Hygiene?

Answer 30

Shampoo | air conditioner

Question 31

What are the benefits of chemical reactions in Healthcare?

Answer 31

Antacids which neutralise hydrochloride acid

Question 32

What are the benefits of chemical reactions in Cooking`?

Answer 32

Combustion which provide heat to cook food

Question 33

What are the benefits of chemical reactions in Manufacturing?

Answer 33

Raw materials can be changed into useful products, for example manufacture of plastic, paint