Paper 6

Question 1

When a the gas collecting tube is upside down, give a property of this gas

Answer 1

It is less dense than air

Question 2

Why is a pencil used in drawing the origin line in chromatography?

Answer 2

If pen was used it will dissolve giving colors and so the experiment won’t be accurate

Question 3

When using ethanol, give a better apparatus arrangement, and why?

Answer 3

Cover apparatus with a lid bc ethanol is volatile

Question 4

In tests and observation tables, when in the first row, they tell upon heating condensation occurred, there will be a question asking what does this show about the solid?

Answer 4

It is hydrated

Question 5

When copper is used in a test

Answer 5

Light blue precipitate which is soluble in excess to form dark blue solution

Question 6

Why is the experiment done in a fume cupboard?

Answer 6

It releases harmful gases that are poisonous and toxic

Question 7

Why should the solid be crushed?

Answer 7

It increases surface area for a faster rate if reaction

Question 8

Why is the experiment made in a well-ventilated room?

Answer 8

To prevent the burning of a substance

Question 9

Explain the term decant

Answer 9

Filter/pour liquids leaving solid alone

Question 10

Why is concentrated sulphuric acid not used to dry ammonia ?

Answer 10

Because it will react with the base ammonia, which is a neutralization reaction

Question 11

Why should samples be taken from different parts of the field?

Answer 11

To get more accurate results

Question 12

Suggest why it is important to know the ph of the soil

Answer 12

To see which is the best place for growing and what kind of base to use for neutralizing it

Question 13

What is necessary for rusting?

Answer 13

Water(humidity) and oxygen (air)

Question 14

Suggest why in an experiment for rusting the water level increases

Answer 14

Oxygen is used up and water is used to take its place

Question 15

For electrolysis, state the observations

Answer 15

The bulb will light, a metal is formed at the cathode, fizz if gas is produced

Question 16

Suggest suitable materials for electrodes

Answer 16

Graphite
Carbon
Steel

Question 17

When copper is reacted with hydrogen , what is the colour change?

Answer 17

Black to brown because copper oxide is reduced to copper

Question 18

How can you distinguish between water and ethanol?

Answer 18

Use cobalt chloride paper, it turns from pink to blue with water, but no change with ethanol

Question 19

How can you distinguish between sulphuric acid and aqueous sodium sulphate?

Answer 19

There are three tests.

1. You can use a metal carbonate in Which Co2 will be produced with sulphuric acid but there will be no change with sodium sulphate
2. You can add a metal which hydrogen is produced with sulphuric acid, but no change with sodium sulphate
3. Use an indicator like litmus paper. With sulphuric acid with will turn red. With sodium sulphate there is no change

Question 20

How can you distinguish between hydrochloric acid and nitric acid ?

Answer 20

Add silver nitrate in which white ppt will be formed with hydrochloric acid. But there is no reaction with nitric acid

Question 21

What is he purpose of the mineral wool?

Answer 21

To absorb and hold the liquid

Question 22

When there is a delivery tube involved in a question, what precaution should be taken in the experiment when the heat is removed?

Answer 22

Remove the delivery tube to prevent suck- back

Question 23

How can you distinguish between an alkanes and alkenes?

Answer 23

Use bromine water , in Alkene it will go colour less. In an Alkane it will remain orange

Question 24

How can you distinguish between chlorine and sodium chloride?

Answer 24

Add litmus paper, it will bleach with chlorine but nothing happens with sodium chloride

Question 25

How can you distinguish between copper sulphate and copper carbonate?

Answer 25

Acidify with hydrochloric acid, and add barium chloride, there will be a white ppt with sulphate but no white ppt with carbonate
OR just add hcl in which nothing happens with sulphate, but fizz or effervescence of co2 will occur with carbonate

Question 26

When a measuring cylinder is used how could you change the apparatus for more reliable results?

Answer 26

A biuret can be used instead

Question 27

What happens if the reagent is more concentrated

Answer 27

Volume if reagent decreases if it is more concentration

Question 28

Concentrated acid

Answer 28

An acid that contains a large number of H+ hydrogen ions. Vice versa with dilute acid

Question 29

Concentrated base

Answer 29

A base that contains a large number of OH- hydroxide ions. Vice versa with a dilute base

Question 30

Strong acid

Answer 30

And acid that ionizes completely giving H+ in solutions. Vice versa with a weak one

Question 31

Strong base

Answer 31

Is one that ionizes completely giving OH- in solutions. Vice versa for a weak base

Question 32

Concentrated

Answer 32

A solution that contains a large number of solute or little amount of water is involved.

Question 33

How can crystals be made?

Answer 33

1. Heat till point of crystallization
2. Leave to cool gradually
3. Filter, dry and collect crystals

Question 34

How can you detect the point if crystallization?

Answer 34

Place a stirring rid in the solution and see the formation if the first crystals on it

Question 35

What is the purpose of ice or cold water?

Answer 35

To cool down the gas so that it condenses and turns into liquid