(i)

The gas which is used in both rusting and burning is oxygen

(ii)

Ways in which rusting can be prevented in everyday life

1. Painting
2. Galvanizing (electroplating)
3. Greasing
4. Oiling
5. Alloying

(i)

Green grass → grasshopper → bird

OR

Green grass → goat → man

(ii)

Diseases that can be controlled by immunization

1. Tuberculosis
2. Measles
3. Poliomyelitis
4. Whooping cough
5. Diphtheria
6. Tetanus
7. Yellow fever
8. Cholera

(i)

Potential energy → Kinetic energy → Sound energy → Heat energy

(ii)

Appliances which use electromagnets in their operation

1. Telephone receivers
2. Loudspeakers
3. Electric bells
4. Burglar alarms
5. Microphones

(iii)

Ways in which a magnet can lose its magnetism

1. Heating the magnet in fire
2. Striking the magnet continuously with a hammer
3. Placing it in a solenoid through which an alternating current flows

(i)

Types of forces

1. Force of gravity
2. Weight
3. Magnetic force
4. Electrostatic force
5. Frictional force
6. Centripetal force
7. Viscous force
8. Tensional/Elastic force
9. Adhesion
10. Cohesion
11. Centrifugal force

(ii)

1. Tensional/Elastic force
2. Force of gravity
3. Frictional force

(iii)

1. Tension/elastic force in the rubber band of the catapult pushed the stone
2. Force of gravity brought down the mango
3. Frictional force acts between the stone and the mango/between the leather of the catapult and the stone/between the palm and the stick of the catapult

i)

Simple machine is a device that makes work easier/faster.

OR

Simple machine a device which enables a small force (effort) to overcome a large force (load).

ii)

Examples of a simple machine

1. Lever (Examples are a crowbar, claw hammer, a pair of pliers)
2. Wheel and axle (Examples are the steering wheel of a car, bicycle pedal)
3. Pulley (Examples are a pulley used in raising a load)
4. The inclined plane (Examples are ramps, staircases, hilly roads)
5. The wedge (Examples are knife, axe, plough)
6. Screw (Examples are A screw bolt)

i)

Rusting is the reaction of iron or iron containing substances with water/moisture and air/oxygen to form an oxide of iron.

ii)

Effects of rusting

1. It causes iron to lose its strength/structure resulting in accident
2. It can cause collapse of building and bridges resulting in maintenance cost
3. It causes iron to lose its lustre

i)

Food nutrients are substances which when taken in by living things help in performing of life activities

OR

Food nutrients are essential materials/substances present in food which when taken in by living things help in performing of life activities

ii)

Carbohydrate → Bread, maize
Fats and oil → Palm fruits, margarine
Protein → Beans, meat

i)

Effects of malnutrition in farm animals

1. Loss of weight/stunted growth
2. General body weakness
3. Reduced activity
4. Dullness
5. Less resistant to diseases
6. Reduced reproduction
7. Poor formation of bones

ii)

Viral diseases of farm animals

1. Rinder-pest
2. Newcastle
3. Gumboro
4. Fowl pox
5. Cow pox
6. Marek's disease
7. Swine fever
8. Bird flu
9. Foot and mouth disease

i)

Fertilization is the fusion of the male and female sex cells to form a zygote.

ii)

The processes that lead to fertilization in humans after mating

1. The sperms move through the vagina, cervix and uterus to the fallopian tube
2. Only one of the millions of sperms succeeds to penetrate the membrane of the ovum
3. The nuclei of the sperm and ovum unit/fuse to form a zygote

i)

Density of a substance is the mass per unit volume of the substance.

OR

Density = $\frac{\mathrm{Mass\; (M)}}{\mathrm{Volume\; (V)}}$

ii)

Determination of the density of a 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)

An element is a substance that cannot be broken down/split into simpler substances by any known chemical means.

ii)

(i)

Vegetative reproduction is the propagation of new individuals of a particular species by means of parts of a parent plant other than (fertilized) seeds.

OR

Vegetative reproduction is a form of reproduction whereby plants reproduce young ones from growing parts or buds of the parent plant.

(ii)

Differences between sexual reproduction and vegetative reproduction

(iii)

Advantages of vegetative reproduction

1. Results in species of the same characteristics/features
2. Stores enough food reserve for the offspring
3. Growth is more rapid/fast
4. Only one parent is required to produce the offspring/does not require any agent as in pollination

(i)

(ii)

Solute

(i)

Second class lever

(ii)

I → Effort
II → Load
III → Pivot/Fulcrum

(iii)

Examples of second class levers

1. Wheelbarrow
2. Bottle opener
3. Nutcracker
4. Staplers
5. Nail clippers
6. Doors or gates

i)

Magnetic field is a region/area around a magnet/moving electric charge within which the force of magnetism acts/can be felt/experienced

ii)

Methods of making magnets

1. By induction
2. By stroking
3. By the use of electricity
4. By hammering/hitting

i)

calcium chloride → CaCl₂

ii)

copper (I) oxide → Cu₂O

iii)

nitrogen (IV) oxide → NO₂

iv)

ammonia → NH₃

i)

Physical properties of soil

1. Texture
2. Structure
3. Temperature
4. Colour
5. Permeability
6. Water
7. Capillarity
8. Organism
9. Drainage
10. Air
11. Strength/consistence
12. Porosity

ii)

Texture of clayey soil

It is smooth/slippery/sticky when wet