Question 1

Select the correct definition of a pure substance.

Accepted Answer

A pure substance is one that is made up of just one substance. That substance can be either an element or a compound.

Answer

A pure substance is one that is made up of just one substance. That substance is always an element.

Answer

A pure substance is one that is made up of no more than two substances.

Answer

A pure substance is something that boils at 100 °C.

Question 2

Which substance is pure?

Accepted Answer

water

Answer

orange juice

Answer

paint

Answer

make-up

Question 3

Which of the following properties are known as the fixed points for an element or compound?

Accepted Answer

melting point

Answer

density

Answer

relative formula mass

Answer

solubility

Question 4

The melting points of substances A, B, C, and D were obtained. Use the information in the table to decide which of the substances contains impurities.

Accepted Answer

A and C

Answer

D only

Answer

A only

Answer

B and D

Question 5

Paper chromatography was carried out on four unknown substances A, B, C and D. The chromatogram is shown below. Which substance is pure?

Accepted Answer

C

Answer

B

Answer

A

Answer

D

Question 6

Choose the statement that correctly describes the melting points of pure and impure substances.

Accepted Answer

Pure substances have fixed melting points and boiling points but impure substances melt or boil over a range of temperatures. The more impurities present, the wider this range will be.

Answer

Pure substances have different melting points and boiling points but impure substances melt or boil over a range of temperatures. The more impurities present, the smaller this range will be.

Answer

Impure substances have fixed melting points and boiling points but pure substances melt or boil over a range of temperatures. Impurities generally lower the melting point and make the boiling point higher.

Answer

Pure substances have fixed melting points and boiling points but impure substances melt or boil over a range of temperatures. The more impurities present, the smaller this range will be.

Question 7

A gas relights a glowing splint. Which gas is it?

Accepted Answer

oxygen

Answer

chlorine

Answer

hydrogen

Answer

carbon dioxide

Question 8

Which statement about paper chromatography is correct?

Accepted Answer

Components with the greatest attraction to the stationary phase will travel the least.

Answer

The stationary phase is the solvent.

Answer

Paper chromatography can be used to separate compounds but not identify them.

Answer

The mobile phase is the spots.

Question 9

Use the information in the table below to decide which substance is the purest.

Accepted Answer

B

Answer

D

Answer

C

Answer

A

Question 10

Choose the statement that gives the correct interpretation of this chromatogram.

Accepted Answer

A is a mixture that contains B and C and an unknown substance

Answer

A does not contain B or C

Answer

A is a mixture that contains B and C

Answer

A is a mixture containing B and an unknown substance

Question 11

Calculate the Rf value for substance C.

Accepted Answer

0.35

Answer

0.58

Answer

30.7

Answer

2.8

Question 12

What type of chemical reaction happens between
carbon dioxide and limewater?

Accepted Answer

Neutralisation

Answer

REDOX

Answer

Reduction

Answer

Oxidation

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