10 chemistry questions – The Science Site

1. What kind of substance is air

a mixture of elements and compounds

a mixture of elements

an single element

a mixture of compounds

2. What is NOT true about air

There is no air on the moon

Air is a mixture of gases

Air is made up mostly of a gas called nitrogen

Air does not weigh anything

3. If hydrated copper sulphate is heated until it has all decomposed the solid product will: .....

weigh less than the original solid

react with water to form a white compound

weigh more than the original solid

be blue in colour

4. What happens to water if it is left to boil in a kettle

It dissolves

It evaporates away

It melts

It freezes

5. Some copper foil is heated in a sealed test tube until the copper stops changing colour.
What colour does the copper become?

White

Black

Blue

Yellow

6. What percentage of the air is argon (approximately)?

21%

50%

78%

1%

7. Name a substance with a pH value equal to pH7

Lemon juice

Limewater

Hydrochloric acid

Water

8. Exactly enough sodium hydroxide solution is added to hydrochloric acid to make a neutral solution.
How can salt (sodium chloride crystals) be obtained from the resulting solution?

Warming the solution so that the water evaporates.

Adding calcium chloride solution which will make the salt precipitate.

Passing electricity through the solution.

Filtering the mixture.

9. Which of the properties of water listed below is NOT correct

Water is a colourless liquid

The bowling point of water is 100 ?C

When water turns into ice its volume gets slightly less

A cloud is made of tiny droplets of condensed water

10. What colour will universal turn when mixed with water?

Purple

Yellow

Red

Green