Correct Answer: D. glucose

Explanation

(a)(i) Aluminium is preferred to copper for making overhead electric cables because aluminium: is lighter/has a lower relative density

-is more resistant to corrosion.

(ii) Extraction of aluminium from purified bauxite. A solution of the pure alumina in molten cryolite (Na\(_3\)AIF\(_6\)) is placed in the electrolytic cell made of iron lined with graphite which serves as the cathode. The anode consists of graphite rods dipping into the electrolyte (solution of alumina in molten cryolite). The cell is maintained at high temperature 900 ± 100°C. At the cathode: Al\(^{3+}\) + 3e\(^-\)m ---> Al ; At the anode: 2O\(^{2-}\) ---> O\(_2\) + 4e\(^-\). The molten aluminium collects at the bottom of the cell and is tapped off at intervals.

(b) Illustration of the cell used for the purification of copper.

(i) Electrode I increases in mass during the electrolysis, because Cu\(^{2+}\) migrate to it. The Cu\(^{2+}\) is reduced to copper/Cu\(^{2+}_{(aq)}\)+ 2e --> Cu\(_{(s)}\) and the copper is deposited, leading to an increase in its mass.

(ii) Electrode II is the site of oxidation. Oxidation is electron loss and the reaction at this electrode is Cu -> Cu\(^{2+}\) + 2e\(^{2+}\)

(iii) Ill is CuSO\(_{4(aq)}\)/any soluble copper (II) salt. Its colour does not change in intensity because Cu\(^{2+}\) which is responsible for the colour is removed by the cathode (i) from the solution and is replaced by the anode.

(c) To calculate the current that will deposit 8.00g of calcium from fused CaCl\(_2\) in 1 hr. 15mins.

Ca\(^{2+}\) + 2e\(^{-}\) -> Ca.

40g of calcium will be deposited by (2 x 96500)C

8.00g of calcium will be deposited by \(\frac{8 \times 38600}{40}\) = 38600 C ; Let x represent 386000C

Q = It xc = 1 x 75 x 60 ;

Current (I) = \(\frac{x}{75 \times 60}\) ; Current = 8.58

Explanation

(a) A contract is an agreement between two or more parties that is enforceable by law.

(b) Situations under which a contract can be brought to an end are:

(i) When there is an alteration of a written law affecting the contract.

(ii) When one of the parties breaches or if one of the parties refuses to carry out his own obligation in a contract.

(iii) When all the parties to the contract have carried out their obligations to the contract.

(vi) When one of the parties expresses desire not to go ahead with the contract provided such withdrawal does not constitute any loss to the other party.

(v) When the parties voluntarily agree to discontinue the contract especially when negative results are imminent

(vi) If the subject of contract is illegal, e.g prostitution or contract with a minor below the age of 18 years, the contract can be terminated except contract of necessity.

(vii) If the contract becomes frustrated by an act of God, e.g. flood, disaster, death, war, etc.

(viii) If the law discontinues the contract owing to bankruptcy.

Correct Answer: D. registration of eligible voters

Explanation

- For an election to be free and fair, eligible voters must be registered and certain civil liberties, such as the freedoms of speech, association and assembly, are required.

Correct Answer: A. forbidden even in small quantity

Correct Answer: C. Methylpropanoate

Correct Answer: D. 30g

Correct Answer: C. #19,950

Correct Answer: C. tangent to the isocost

Explanation

The firm is in equilibrium at the point where the isoquant curve is tangent to the iso-cost line. At this point, the firm is maximising its output level by employing the optimal combination of capital and labour.

Explanation

(a) This can either be done using the long division method (easier) or convert everything to base ten and divide, then re-convert to base two.

I'll be using the latter method.

\(11111111_{two} = 1 \times 2^{7} + 1 \times 2^{6} + 1 \times 2^{5} + 1 \times 2^{4} + 1 \times 2^{3} + 1 \times 2^{2} + 1 \times 2^{1} + 1 \times 2^{0}\)

= \(128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255_{ten}\)

\(101_{two} = 1 \times 2^{2} + 0 \times 2^{1} + 1 \times 2^{0} \)

= \(4 + 0 + 1 = 5_{ten}\)

\(\frac{255}{5} = 51_{ten}\)

= \(110011_{two}\)

(b)

(i) Length of arc AXB = \(\frac{105}{360} \times 2 \times \frac{22}{7} \times 6cm\)

= \(11cm\)

\(\therefore Perimeter = 6cm + 11cm + 6cm = 23cm\)

(ii) Area of sector = \(\frac{105}{360} \times \frac{22}{7} \times 6cm \times 6cm\)

= \(33 cm^{2}\)