Correct Answer: D. grasping prey

Explanation

(a) Factors considered in choosing an irrigation system in West Africa

- Cost of irrigation system

- soil type

- availability ofwater

- topography/slope of land

- type of crop to be cultivated

- size of farmland

(b) Problems associated with irrigation in West Africa

- Irrigation equipment is expensive to install

- Inadequate water supply for irrigation in certain areas and periods

- Maintenance cost is high

- Inadequate technical know

- how on the use of irrigation schemes among farmers

- The high relative humidity on irrigated land favours the growth of disease-causing organisms

- Salts that are toxic to crops could be introduced to the farmland through irrigation water

- Some irrigation systems disturb free movement of farm machinery

- Damage of source of water supply may render the irrigation system ineffective or cause destruction of immediate environment

- Water loving plants are likely to proliferate as a result of moisture in the soil leading to weed infestation

(c) Area of farmland in hectares Length = 0.4km = 400m lmk

Breath = 2,400m

Area of rectangle = length x breath lmk

Area of farmland 400m x 2,400m = 960,000m\(^2\) lmk

1 Hectare = 10,000m\(^2\) Area of farmland in hectares = \(\frac{960 000}{10,000}\) Imk

= 96 hectares lmk

(d) Primary and secondary tillage implements

Primary tillage implement

Plough/mouldboard plough/disc plough/chisel

plough 1mk

Secondary tillage implemens

- harrow/disc harrow ridger

- cultivator

- rotavator

Correct Answer: B) 1.8J

Correct Answer: C. letter

Correct Answer: (a) 1985

Correct Answer: B) 2/3

Explanation

(a)(i) Diffusion is the movement of particles from the region of higher concentration to the region of lower concentration

(ii) Charles' Law states that the volume of a given mass of gas is directly proportional to its absolute temperature at a constant pressure.

(iii)

(iv) \(\frac{V_1}{T_1} = \frac{V_2}{T_2}\) \(T_2 = \frac{T_1V_2}{V_1}\)

\(T_2 = \frac{300 \times 300}{150} = 600k\)

(v)(i) Solid < liquid < gas / solid, liquid, gas

(ii) Gas < liquid < Solid / gas, liquid, solid

b)(i) In a reversible reaction at equilibrium, if any will of the factors affecting the equilibrium is altered, the position of equilibrium will change so as to annul the effect of the change

(ii) Oxide I

% of O\(_2\) = 11.1 %

% by mass of metal = 88.9%

11.1 of O\(_2\) combined with 88.9 of metal

100 of O\(_2\) = \(\frac{100}{88.9}\) = 800.9g

Oxide II

% of O\(_2\) = 20%

% by mass of metal = 80%

20 of O\(_2\) combined with 80 of metal

100 of O\(_2\) = \(\frac{100}{ 80}\) = 400g

Ratio of metal in both oxides = 800. 9 : 400

2 : 1

(c)(i) Add water to mixture A, B and C and stir.

— C dissolves

— Filter to obtain C as filtrate and A and B as residue

— Heat residue until melted.

— Separate by simple distillation

— Evaporate filtrate to dryness to obtain solid C

— Pure A is collected at 117°C and pure B at 160°C

(ii) Mass of mixture = 25.25g

Mass A + B = 7.52g + 8.48g

= 16.00g

Mass of C = 25.25 - 16.00g

= 9.25g

% of C in mixture = \(\frac{9.25}{25.25}\) x 100

= 36.6%

Correct Answer: D. timidly

Correct Answer: A. -4

Explanation

Substituting for x in the equation

\(2(2)^2 + (k+2)2+k = 0 \Rightarrow 8 +2k + 4 + k =0 \Rightarrow 3k =-12; k=-4\)

Correct Answer: D. oxygen