i)

Physical properties of water

1. Odourless
2. Colourless
3. Tasteless/insipid
4. Freezes at 0^oC
5. Boils at 100^oC
6. Universal solvent
7. Exists in three states
8. Has a density of 1g/cm³ (at 4^oC)
9. It is transparent
10. It has a neutral pH/pH = 7
11. High surface tension

ii)

Why water is neutral

When red litmus paper or blue litmus paper is dropped in a sample of water, there is no change in colour.

i)

Functions of nitrogen in plants

1. For plant growth/vegetative growth
2. Increases yield of straw
3. A constituent of organic compound of plants
4. For plant development
5. Increases seed and fruit production
6. To make proteins
7. To make chlorophyll

ii)

Functions of potassium in plants

1. Plays an important role in plant metabolism
2. Plays an important role in translocation of starch to growing parts
3. Plays an important role in carbohydrate formation
4. Neutralization of organic acids
5. Strengthens straw and stalk of plants
6. Aids absorption of nutrients
7. Helps to reduce diseases in plants
8. Helps to produce quality fruit and promotes seed development
9. Activates enzymes for photosynthesis and respiration
10. Helps build proteins
11. Aids absorption of nutrients

i)

Human activities that disrupt the carbon cycle

1. Destruction of forest/cutting of trees/lumbering
2. Bush burning
3. Burning of fossil fuels

ii)

Effects of the disruption of the carbon cycle on the environment

1. Global warming/rise in temperature/greenhouse effect/affects climate
2. Reduction in oxygen
3. Rise in sea level/flooding/melting of ice
4. Animals/plants become endangered/extinct
5. Prolonged drought
6. Reduction in rainfall

i)

Density is the mass per unit volume of a body

OR

Density = $\frac{\mathrm{Mass}}{\mathrm{Volume}}$

ii)

Density = $\frac{\mathrm{Mass}}{\mathrm{Volume}}$

Density x Volume = Mass

Divide both sides by Density

Volume = $\frac{\mathrm{Mass}}{\mathrm{Density}}$

Mass = 50 kg
Density = 2kg/m³

Volume = $\frac{50}{2}$ = 25 m³

(i)

Erosion is the washing away/the removal and carrying away of the top soil by running water, rain or wind.

(ii)

Reproduction is the process by which living organisms give rise to/produce young ones of their own kind.

(iii)

Parasite is any organism/living thing that lives in or on another organism/living thing called the host for its food and by so doing causes harm to the host.

(iv)

Excretion is the process of removing metabolic waste/substances from the body of a living organism.

(i)

Work is said to be done when the point of application of a force moves an object through a distance in the direction of the force.

OR

Work is said to be done when a force moves a body through a distance in the direction of the force.

OR

Work is the product of force and the distance moved in the direction of the force.

OR

Work = Force x distance moved in the direction of the force

(ii)

Work = Force x Distance moved in the direction of the force

Work = 300 J
Distance = 10 m

300 J = Force x 10 m

Divide both sides by 10 m

Force = $\frac{\mathrm{300\; J}}{\mathrm{10\; m}}$ = 30 N

(i)

NH₄Cl → Ammonium chloride

(ii)

HCl → Hydrochloric acid/Hydrogen chloride

(iii)

CuSO₄ → Copper (II) sulphate/Copper (II) tetraoxosulphate (VI)

(iv)

FeCl₃ → Iron (III) chloride

(i)

Organic farming

By using plant and animal based materials (1 mark) in the farming process, without use of agrochemicals/using organic fertilizers/biological pesticides (1 mark)

2 marks

(ii)

Mixed farming

By growing of crops and raising of animals on the same farm/plot (1 mark) at the same time/season (1 mark)

2 marks

(iii)

Mixed cropping

By growing of two or more arable crops on the same piece of land, (1 mark) (without any sequence or arrangement) at the same (1 mark)

2 marks

(i)

Oil and water → Heterogeneous (1 mark)

(ii)

Salt and water → Homogeneous (1 mark)

(iii)

Ethanol and water → Homogeneous (1 mark)

(i)

Reasons why energy from the sun is said to be renewable

1. Energy from the sun is continuous/constantly replenished (1 mark)

2. Energy from the sun does not get exhausted/inexhaustible within a human time scale/non-depletable (1 mark)

2 marks

(ii)

Differences between heat and temperature

Any 3 x 1 mark = 3 marks

(i)

Effects of leaching on the Nitrogen cycle

1. During heavy rainfall, nitrates in the soil are washed out of the root zone of plants (1 mark)

2. And cannot be taken in by animals, (1 mark) preventing the return of the nitrogen into the soil as nitrites (1 mark)

3 marks

(ii)

Effects of removal of leguminous plants on the Nitrogen cycle

1. This results in the removal of nitrogen-fixing bacteria (1 mark)

2. Thereby preventing the conversion of atmospheric nitrogen to ammonia (1 mark)

3. Eventually denying the soil nitrates and subsequently interrupting the cycle (1 mark)

3 marks

i)

An acid is a proton donor

OR

An acid is a substance/compound that produces excess hydrogen ion (H⁺) in water.

An acid is a substance that contains replaceable hydrogen.

ii)

Differences between an acide and a base

i)

Pressure is force per unit area or the force acting (normally) per unit area

OR

Pressure = $\frac{\mathrm{(Normal)\; Force}}{\mathrm{Area}}$

ii)

Force = 200 N

Area = 50 m²

Pressure = $\frac{200}{50}$

Pressure = 4 Nm^-2 or 4 Pa

i)

Unicellular is a living organism that consists of only once cell.

ii)

Multicellular, living organisms that consist of many cells.

(i)

Density is the mass per unit volume of a substance

OR

Density = $\frac{\mathrm{Mass}}{\mathrm{Volume}}$

(ii)

Determination of the density of stone

1. Measure/weigh the mass of stone by means of a beam/chemical balance as M g
2. Fill a large measuring cylinder with water to a suitable level and record the volume as V₁ cm³
3. Tie the stone with thread and gently lower it into the water in the measuring cylinder and record the new volume as V₂ cm³

The density of the stone is then calculated as follows:

Volume of stone = V₂ cm³ - V₁ cm³

Mass of stone = M g

Density = $\frac{\mathrm{Mass}}{\mathrm{Volume}}$

Density of the stone = $\frac{\mathrm{M\; g}}{({\mathrm{V}}_2-{\mathrm{V}}_1){\mathrm{cm}}^3}$

(i)

Alcohol and water → Distillation/fractional distillation

(ii)

Salt and water → Distillation/Evaporation and condensation

(iii)

Powdered charcoal and iron filings → Use of magnet

(iv)

Powdered chalk and water → Filtration/decantation

(i)

Conditions that are required for photosynthesis to take place

1. Presence of sunlight/light
2. Presence of carbon dioxide
3. Presence of chlorophyll
4. Suitable temperature/warmth
5. Water/mineral salts

(ii)

How to show that starch is formed during photosynthesis

1. Two leaves are plucked, one from a plant exposed to sunlight for at least two hours and the other from plant kept in the dark for the same period
2. Both leaves are boiled in water to kill the cells
3. Both leaves are boiled in alcohol to remove pigmentation/chlorophyll
4. Both decolourized leaves are washed in warm water to soften them
5. Dip both leaves in iodine solution
6. The leaf plucked from plant in the sunlight turns blue black with iodine showing the formation of starch during photosynthesis
7. The leaf plucked from plant kept in the dark remains colourless showing there was no formation of starch because photosynthesis did not take place

(i)

A satellite is an object that moves around a larger object in space.

OR

A satellite is an artificial body placed in orbit round the earth or another planet.

(ii)

Examples of natural satellites

1. Moon
2. Earth

Note: any named planet is also an example of a natural satellite

(iii)

Uses of artificial satellite

1. For exploring the planets/moons
2. For scientific research/experimental research/internet
3. To study the universe
4. For communications/broadcasting/telephone call
5. For weather forecast/collecting information on the weather
6. Map making
7. Spying
8. For navigation/satellite for navigation
9. Military purposes