i)

Surface tension is the property of a liquid which makes the surface behave as if it were a stretched elastic skin.

ii)

Household devices that make use of surface tension

1. Umbrellas
2. Raincoats
3. Tents
4. Canopies

iii)

Umbrellas/Raincoats/Tents/Canopies made of canvas do not leak because the surface tension of the water prevents the water from passing through the tiny holes in them

OR

In umbrellas/raincoats/tents/canopies made of canvas, water forms films like stretched elastic skin over each pore which prevents water from passing through.

i)

Constipation is the difficulty in freeing/expelling faces from the bowels regularly.

OR

Constipation is the difficulty in defecating regularly.

OR

Constipation is the irregular and difficult passage of faeces.

ii)

Ways by which constipation can be prevented

1. Take meals at regular times
2. Do not overeat
3. Undertake a good amount of exercise
4. Take in enough water
5. Eat plenty of fruits, vegetables and rouphages
6. Free bowels regulary/attend nature's call regularly

i)

Blue

ii)

Reaction is complete

OR

Reaction is slightly acidic

OR

Sodium hydroxide has been neutralized

iii)

Sodium chloride/NaCl/common salt

iv)

NaOH + HCl → NaCl + H₂O

i)

An anion is a negatively charged atom or group of atoms

OR

An anion is a negatively charged ion

OR

An anion is an ion formed when an atom or group of atoms gain electron(s)

ii)

i)

Electromagnetism is the production of a magnet by the use of electric current.

ii)

The key is switched on and off few times. When the pin is removed and tested, it is found to be magnetized.

i)

Characteristics of roots

1. They generally grow into the soil
2. They grow away from light
3. They are usually brownish in colour/possess no chlorophyll
4. Their tips are protected by root caps
5. They bear root hairs
6. They develop from the radicle of the embryo

ii)

Functions of roots

1. They anchor/hold/support the plants firmly in the soil
2. They absorb water and dissolved mineral salts from the soil
3. They store excess food in some plants
4. They are responsible for exchange of gases in some plants in marshy habitats
5. In some plants, the roots are a means of reproduction
6. They transport/send water and mineral salts into the stem

i)

sodium chloride → NaCl

ii)

copper sulphate → CuSO₄

iii)

magnesium sulphate → MgSO₄

iv)

potassium carbonate → K₂CO₃

i)

iodine and sand → Sublimation

ii)

ethanol and water → Distillation

i)

Digestion is the breaking down of complex or insoluble food substances into simple and absorbable forms in the body of mammals.

ii)

How food is digested in the stomach

1. Slightly alkaline food enters the stomach
2. The walls of the stomach produce/secrete gastric juice which is mixed with the food
3. The gastric juice contains dilute hydrochloric acid and protein digesting enzymes (proteases)
4. The dilute hydrochloric acid provides/creates acidic medium/condition in the stomach
5. The enzymes break down the large protein molecules into simpler units (amino acids)
6. Only protein molecules are digested in the stomach

i)

Eclipse of the sun is the blocking of the light from the sun by the moon from reaching portions/parts of the earth.

OR

Eclipse of the sun occurs when the moon comes between the sun and the earth so that the moon's shadow is cast on the earth.

ii)

Total and partial eclipse

The shadow which the moon casts over the earth has both umbra (total darkness) and penumbra (partial darkness).

People in the direct region of the eclipse observe total darkness/umbra which is the total eclipse.

Those slightly out of the region observe partial darkness/penumbra which is the partial eclipse.

People outside the shadow regions will see the sun as normal.

i)

Differences between a physical change and a chemical change

ii)

Examples of a physical change

1. Dissolving sugar in water
2. Sand and sugar mixture
3. Sulphur and iron filing mixture
4. Melting of candle
5. Melting of ice
6. Expansion of copper
7. Filtration
8. Freezing of water
9. Grinding of chalk
10. Boiling of an egg for five minutes
11. Chewing of meat in the mouth for two minutes
12. Pounding of boiled cassava and plantain together into fufu

Examples of a chemical change

1. Burning wood
2. Reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl)
3. Rusting of iron
4. Cooking of food
5. Fermentation
6. Chewing of piece of bread in the mouth for two minutes