(i)

(ii)

Observations in set-up A

The pressure of the water coming out of the lower hole is higher than the one at the top.

Observations in set-up B

The pressures of the water coming out of the holes are the same because they are at the same level.

(iii)

The aim of set-up A is to show that pressure increases with depth in a liquid.

(iv)

The aim of set-up B is to show that pressure at the same point/level in a liquid is the same.

(i)

The volume of solution C = Volume of solution A + Volume of solution B

The volume of solution C = 20 cc + 20 cc

The volume of solution C = 40 cc

(ii)

(iii)

Neutralization reaction

(iv)

Sodium chloride solution/NaCl solution/salt solution/brine

(v)

The water evaporates leaving solid sodium chloride/NaCl

OR

Solid sodium chloride/NaCl/common salt is formed

OR

Solution becomes concentrated

(i)

I → to stop further starch formation/stop photosynthesis process/kill the cells
II → to remove the green pigment/to decolourize the leaf/to remove chlorophyll
III → to soften the leaf

(ii)

Leaf turns blue black

(iii)

Green → colourless/white → blue black

(iv)

The alcohol will catch fire when heated over naked fire.

(vi)

No blue black colour will be seen/colour of iodine will be seen because starch is absent.

i)

Note:

Arrows on lines of force should point away from the north pole toward the south pole

ii)

Efficiency = $\frac{\mathrm{Work\; Output}}{\mathrm{Work\; Input}}$ x 100%

Work input = 30 J, work output = 25 J

Efficiency = $\frac{25}{30}$ x 100% = 83.33%

(i)

Difference between unicellular organisms and multicellular organisms

Unicellular organisms have only one cell but multicellular organisms have many cells.

(ii)

Reasons why vegetable crops are important to humans

1. Contain nutrients(carbohydrates, vitamins and mineral salts) which are needed by the human body for normal growth
2. Some vegetables contain medicinal substances that treat or control various diseases
3. Some vegetables contain proteins which are used for repair and replacement of worn out cells/tissues
4. Some vegetables contain high amount of cellulose/roughage material that prevent constipation
5. They serve as source of food

(i)

Elements of climate

1. Temperature
2. Humidity
3. Atmospheric pressure
4. Wind speed
5. Wind direction
6. Cloud
7. Rain
8. Sunlight/Intensity of light

(ii)

Difference between climate and weather

Weather is the atmospheric condition of a particular place over a short period of time while climate is the average of the atmospheric conditions over a long period of time.

(i)

Corrosion is the wearing away of surfaces (usually metallic) as a result of chemical reactions between surfaces of material and atmospheric gases.

(ii)

Sublimation is the changing of a substance from solid state directly into the gaseous state.

i)

Functions of leaves to the plant

1. They manufacture food for the plant
2. They help in getting rid of excess water in a plant
3. The exchange of gases between the atmosphere and a plant takes place through the stomata on the leaves

ii)

Functions of roots to the plant

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

i)

eating → voluntary

ii)

walking → voluntary

iii)

sneezing → involuntary

iv)

laughing → voluntary

i)

Differences between a physical change and a chemical change

ii)

Chemical equation for the preparation of carbon dioxide

2HCl + CaCO₃ → CaCl₂ + H₂O + CO₂

i)

A machine is a device that helps us to do work easier/faster.

OR

A machine is a device that enables a small force (effort) to overcome a large force (load).

ii)

Efficiency of a machine = $\frac{\mathrm{Work\; output}}{\mathrm{Work\; input}}$

OR

Efficiency of a machine = $\frac{\mathrm{Output\; energy}}{\mathrm{Input\; enery}}$

OR

Efficiency of a machine = $\frac{\mathrm{Mechanical\; Advantage\; (M.A)}}{\mathrm{Velocity\; Ratio\; (V.R)}}$

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)

Symptoms of cerebrospinal meningitis

1. (High) fever
2. (Severe) headache
3. Stiff neck or painful neck
4. Vomitting
5. Fatigue or numbness or weakness in the muscle of arm or hand or shoulder
6. Imbalance or coordination problem

ii)

Symptoms of chicken pox

1. Loss of appetite
2. Tiredness
3. (High) fever
4. Headache
5. Rashes on body or itching
6. Malaise

iii)

Symptoms of typhoid

1. Diarrhea or constipation
2. Abnormal pain
3. (Mild) fever
4. Headache
5. Fatigue or weakness
6. Cough
7. Cough
8. Loss of appetite
9. Vomitting

i)

Energy is the capacity or ability to do work

ii)

Reasons to conserve energy

1. For future use
2. Create a healthier planet
3. Produce a higher quality of life
4. Reduce the energy bills
5. Helps sustain the resources

i)

Methods of restoring soil resources

1. Fertilizer application/organic composting
2. Land rotation
3. Afforestation/re-afforestation
4. Mulching
5. Cover cropping / green manuring
6. Crop rotation with legumes

ii)

Land rotation

1. This is a system of farming in which a farmer cultivates a piece of land for sometime and leaves it to clear a new land when the old land becomes less fertile

2. It helps check the spread of diseases
3. Land regains lost nutrients after the fallow period
4. Checks spread of pests

Cover crop or green manuring

1. Crops/plants are grown to cover the soil to maintain soil fertility/moisture or to enrich the soil
2. They increase the soil organic matter

Crop rotation

1. Involves growing different types of crops in one location across a sequence of growing seasons
2. It reduces soil erosion
3. It increases soil fertility

Mulching

1. Its the process of using garden leftovers such as leaves, green chipping and shredded trees to cover any bare soil in the garden
2. It improves the soil texture and slow moisture evaporation
3. It also returns organic material and nutrients to the soil

i)

Binary compound is a compound formed from two different elements

ii)

α) Li₂O

β) MgCl₂

iii)

Lithium oxide

Note the name of the compound formed in β) is Magnesium chloride