Year 8 ScienceName:Science Teacher:The year 7 topics you are to be assessed are on

Chemical reactionsPathogens

Chemical reactions.

1. (a) Reshma had a mixture of iron filings and sand. What could she use to separate the iron filings from the mixture?

...........................................................1 mark

(b) Reshma put 10 cm3 of water and 2 g of a different solid into each of four test-tubes. She shook each test-tube.The drawings show the test-tubes after 10 minutes.

Asalt

Bsand

Csugar

Dlim estone

Why can the salt and sugar no longer be seen in test-tubes A and C?

.....................................................................................................................

.....................................................................................................................1 mark

(c) Reshma added hydrochloric acid to some pieces of limestone as shown below.

hydrochlo ricacid

lim estonelim ew ater

(i) Look at the diagram above. How can you tell that a gas is given off in this experiment?

.............................................................................................................

.............................................................................................................1 mark

(ii) Reshma passed the gas through limewater. This showed that the gas was carbon dioxide.

What happened to the limewater?Tick the correct box.

It stayed clear.

It turned blue.

It turned cloudy.

It turned red.1 mark

maximum 4 marks

2. Burning fossil fuels causes air pollution.

(a) (i) Give the names of two fossil fuels.

....................................................... and .......................................................1 mark

(ii) Some fossil fuels contain sulphur.

Complete the word equation for the reaction between sulphur and oxygen in the air.

sulphur + oxygen .....................................................................................1 mark

(b) Burning fossil fuels leads to the formation of acid rain.Acid rain has collected in this lake.A helicopter is dropping calcium hydroxide into the lake.

Calcium hydroxide dissolves in water to form an alkaline solution.

(i) What effect does an alkali have on the pH of an acidic lake?

......................................................................................................................1 mark

(ii) When calcium hydroxide reacts with sulphuric acid in the lake a calcium salt is formed.

What is the name of this salt?Tick the correct box.

calcium carbonate calcium chloride

calcium nitrate calcium sulphate

1 mark

(c) The photograph below shows trees damaged by acid rain.

(i) The trees have lost their leaves and have died.Explain why leaves are needed for a tree to grow.

......................................................................................................................

......................................................................................................................1 mark

(ii) What effect does acid rain have on buildings made from limestone?

......................................................................................................................

......................................................................................................................1 mark

maximum 6 marks

3. Jessica was investigating the rusting of iron. She set up five experiments as shown below, and left the test-tubes for three days.

A

D

B

E

C

iron nail in distilled w a ter iron na il in tap w aterw h ich has been bo iled torem ove disso lved gases

iron nail and a chem icalto absorb w ate r vapour

iron na il in sea w ater iron na il in v inegar

Jessica wrote the following results in her book.

Test–tube observation

A

B

C

D

E

nail slightly rusty

nail still shiny

nail still shiny

nail very rusty

nail slightly rusty, bubbles of gas seen

(a) Explain why the nails had not rusted in test-tubes B and C.

in test-tube B ……………………………………………………………………….

………………………………………………………………………………………..

in test-tube C ……………………………………………………………………….

………………………………………………………………………………………..2 marks

(b) In test-tube E the iron nail reacted with the vinegar.

(i) Is vinegar acidic, alkaline or neutral?

………………………………….1 mark

(ii) When the iron reacted with the vinegar, bubbles of gas were formed.What gas was formed?

………………………………….1 mark

(c) Before putting the iron nail in test-tube D, Jessica weighed the nail.After three days she dried and weighed the nail and the rust which had formed.

(i) How did the total mass of the nail and rust compare to the mass of the nail at the beginning?

…………………………………………………………………………………1 mark

(ii) Give the reason for your answer.

…………………………………………………………………………………

…………………………………………………………………………………1 mark

(d) Jessica concluded that the presence of salt in the water made the nail rust more quickly.Explain why she drew that conclusion from her experiments.

………………………………………………………………………………………..

………………………………………………………………………………………..

………………………………………………………………………………………..1 mark

Maximum 7 marks

4. Hydrochloric acid is a strong acid.

(a) Winston used universal indicator solution to find the pH of some hydrochloric acid.

(i) Suggest the colour of the mixture of universal indicator solution and the hydrochloric acid.

...........................................................1 mark

(ii) Suggest the pH of the hydrochloric acid.

...............1 mark

(b) Indigestion can be caused when too much hydrochloric acid is produced in the stomach.Magnesium carbonate can be used to treat indigestion.

Winston crushed some indigestion tablets containing magnesium carbonate. He added them to hydrochloric acid in a test-tube. The mixture fizzed.

hydrochloric acid

crushed indigestiontable t

The word equation for the reaction is shown below.

magnesium + hydrochloric magnesium + carbon + water carbonate acid chloride dioxide

(i) Use the word equation to explain why the mixture fizzed when the reaction took place.

.............................................................................................................

.............................................................................................................1 mark

(ii) Winston continued to add crushed tablets to the acid until the mixture stopped fizzing.Why did the fizzing stop?

.............................................................................................................

.............................................................................................................1 mark

(c) When magnesium carbonate reacts with hydrochloric acid, magnesium chloride is formed.

Which two words describe magnesium chloride?Tick the two correct boxes.

a compound a mixture

an element a salt

a metala solvent

2 marks

(d) It is important that the hydrochloric acid in the stomach is not completely neutralised by indigestion tablets.

Why is hydrochloric acid needed in the stomach?

.....................................................................................................................

.....................................................................................................................1 mark

maximum 7 marks

Health

1. The diagram shows some of the organs of the human body.

oesophagus(gu llet)

bones(ribs)

liver

brain

lung

heart

stom ach

in testine

(a) Give the names of two labelled parts where food is digested.

.................................................... and ...................................................1 mark

(b) Why do we need to chew our food and mix it with saliva?

.....................................................................................................................

.....................................................................................................................

.....................................................................................................................2 marks

(c) (i) Draw one line from each bad habit to the organ it harms.

drink ing too m uch a lcohol

eating enough fibre

sm oking c igare ttes

not

live r

lung

ribs

intestine

bad habit organ

3 marks

(ii) Which organ in the list below can be harmed if we eat too much fat?Tick the correct box.

brain heart

lung ribs

1 mark

Maximum 7 marks

2. The information below was taken from the label of a can of baked beans in tomato sauce.

nutritional information list of ingredients100g provides:

ene rgy 406 kJpro tein 5.4 gto ta l ca rbohydrate 17 .6 gsugar 6.0 gfat 0.4 gfibre 3.7 g

haricot beans, tom ato purée ,w ate r, sugar, m odif ied starch,sa lt, paprika , on ion powder,herb extracts, sp ices

(a) A healthy diet contains a number of groups of substances. The nutritional information lists some of these.

Give one group of substances, needed for a healthy diet, which is missing from the nutritional information.

.................................................1 mark

(b) (i) Which food, shown in the list of ingredients, provides the most protein in this can?

........................................1 mark

(ii) Give one reason why we need protein in our diet.

..........................................................................................................1 mark

(c) (i) Name one food, shown in the list of ingredients, which provides fibre.

........................................1 mark

(ii) Why is fibre needed for a balanced diet?

..........................................................................................................

..........................................................................................................1 mark

Maximum 5 marks

3.The drawings show Sofia taking part in four different sports.

The table below shows the average energy needed for each sport for one hour.

sport average energy need forone hour (kJ)

bowling 1030

tennis 1760

football 2260

running 3700

(a) (i) Sofia plays football for two hours each week. She also goes bowling for two hours each week.Explain why Sofia uses up her food reserves more quickly when playing football than when bowling.

.............................................................................................................

.............................................................................................................1 mark

(ii) Athletes should not drink alcohol before taking part in sport.Give two effects of alcohol which would affect an athlete’s performance.

1. .........................................................................................................

.........................................................................................................1 mark

2. .........................................................................................................

.........................................................................................................1 mark

(b) Some athletes take glucose tablets before a 100 metre race.They can also obtain glucose from starch in their diet.A starch molecule is made up of many glucose molecules joined together as shown below.

part of a molecule of starch

In the digestive system, starch is broken down into glucose:

molecules of glucose

An athlete can obtain energy more quickly by eating glucose rather than starch.Explain why.

.....................................................................................................................

.....................................................................................................................1 mark

maximum 4 marks