10 chemistry questions - The Science Site

1. Which chemical will gain in mass when heated?

Anhydrous copper sulphate

Copper foil

Hydrated cobalt chloride

Iodine

2. What percentage of the air is oxygen (approximately)?

50%

1%

78%

21%

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

A cloud is made of tiny droplets of condensed water

Water is a colourless liquid

The bowling point of water is 100 ?C

When water turns into ice its volume gets slightly less

4. Crude oil can be separated into different substances using what method of separation?

Fractional distillation

Chromatography

Simple distillation

Filtration

5. Powdered wood charcoal (carbon) is mixed with copper oxide and heated strongly.
A red glow is seen to spread though the mixture. When the mixture has cooled a pink residue is seen.

Name the two products of this reaction.

Carbon dioxide and copper

Copper and oxygen

carbon and copper oxide

6.

This diagram shows a Bunsen burner.

Which is the hottest part of the flame?

A

D

B

C

7. Why are pan handles often covered in plastic( or wood)?

plastic is a good heat conductor

plastic is cheap

plastic is black

plastic is a good thermal insulator

8. If a substance contains only one kind of atom it is most likely to be

a mixture

a liquid

an element

a compound

9. A liquid with a pH of 6 would be described as .....

A strong acid

A mild alkali

A weak acid

Neutral

10. Why does iron go a pinky-brown when it touches copper sulphate solution?

Because iron is more reactive than copper and so reacts with the copper sulphate, (displacing the copper from the solution)

Because copper is more reactive than iron

Because the iron forms a thin layer of iron oxide (rust) on the surface