Correct Answer: D. Secondary cell has a very low internal resistance

Explanation

(a) First, change the given linear equation to the gradient- intercept form:

\(2x + y = 6 \implies y = 6 - 2x\)

Thus, \(m_{1} = -2, c = 6\). Thus, for a line to be parallel, the gradient \(m_{2} = -2\) (condition for parallelism).

Using \(y - y_{1} = m(x - x_{1})\), we have

\(y - (-3) = -2(x - 2)\)

\(y + 3 = - 2x + 4\)

\(2x + y = 4 - 3 = 1\)

Thus, the line passing through (2, -3) parallel to 2x + y = 6 is 2x + y = 1.

(b) (i)

(ii) (a) \(2 \Delta (5 \Delta 7) = 2 \Delta 7 = 7\)

(b) \(2 \Delta n = 5 \Delta 7\)

\(2 \Delta n = 7\)

By comparison, n = 7.

Explanation

(a) Disposable Income = Income - Tax

(i) Doctor = $8,000 - (10% of $8,000)

= $8,000 - $800

= $7,200

(ii) Engineer= $7,000 - (12% of $7,000)

= $7,000 - $840

= $6,160

(iii) Civil Servant = $5,000 - (18% of $5,000)

= $5,000 - $900

= $4, 100

(iv) Nurse = $6,000 - (15% of $6,000)

= $6,000 - $900

= $5, 100

(b) Regressive system of taxation

(c) Regressive because the higher income earners pay lower rate of tax while low income earners pay higher rate of tax.

(d)

In the diagram above, the curve is negatively sloped indicating that higher income earners are levied at lower tax rate and vice versa. A regressive system of taxation is one in which the higher income earners pay a lower rate of tax while the lower income earners pay a higher rate of tax.

Correct Answer: D. the use of crude implements in farming process

Explanation

Farming implements used by farmers especially at the rural level has been known to lower productivity due to the amount of labour needed to increase production. These farmers still use outdated farm tools. This is one of the major reason for low productivity in the agricultural.

Correct Answer: C. factual

Correct Answer: C. NDP = GDP - depreciation

Explanation

Net domestic product (NDP) is an annual measure of the economic output of a nation that is adjusted to account for depreciation and is calculated by subtracting depreciation from the gross domestic product (GDP).

Correct Answer: C. Depreciation of currency

Explanation

The economic effect is thus, depreciation of currency tends to increase a country's balance of trade ( exports minus imports) by improving the competitiveness of domestic goods in foreign markets while making foreign goods less competitive in the domestic market by becoming more expensive.

Explanation

(a) Graphite:-hexagonal: Diamond:-letrahedral/octahedral

(ii) Explain briefly why diamond is hard and a non-conductor of electricity while graphite is soft and an electrical conductor: n diamond each carbon atom is covalently bonded to four other carbon atoms forming an interlocking three dimens1onal network hence the hardness. Each of the four valence electrons is localized in a covalent bond hence there are no free mobile electrons, while in graphite each carbon atom is bonded to three other carbon atoms forming large sheets with van der Waal's force between the sheets which can easily slide over one another. One of the valence electrons of each atom is delocalized in a covalent bond and can act as a conductor of electricity OR Diamond is hard because it has a rigid/three-dimensional structure. It has no free/ mobile electrons hence it does not conduct electricity. Graphite has a layered structure held together by weak van der Waal's forces hence it is soft. It conducts electricity because it has free/ mobile electrons.

(bi) State what is Achieved at each of the Following Stages in the Purification of Water for Town Supply:

- Aeration- removes odor/kills bacteria.

- Screening- removal of suspended dirt

- Sedimentary- removal of suspended dirt particles after coagulation.

(ii) Name two Substances Responsible for Hardness in Water:

- Calcium hydrogen trioxocarbonate (IV).

- MagnesIum hydrogen triOxocarbonate(IV).

- Magnesium chloride.

- Magnesium tetraOxOSulphate( Vl).

- Calcium tetraoxosulphate (VI).

- Iron (lI) hydrogen trioxocarbonate(IV).

- Calcium chloride.

- Iron(Il) tetraoxosulphate(VI)

(iii) State two Methods for the Removal of Hardness in Water:

- By adding washing soda (Na\(_{2}\)CO\(_{3}\)). Adding (CaCOH)\(_{2}\) /lime water.

- Using ion-exchange resin / permutit/ zeolite.

- Boiling/ distillation

(iv) Give one Disadvantage of Hard Water:

- Furring of kettle/pipes causes blockage leading to power wastage/ scales in the boiler.

- Soap is wasted/ forms scums

- Cannot be used in dyeing/ tanning

- Not suitable for laundry.

- Not suitable for textile industry

(c) Describe Briefly the Extraction of Tin from its Ores:

(i) The ore is concentrated/crushed and washed with water, it is then roasted in air to remove impurities. The product is mixed with charcoal/carbon /coke and heated to reduce the oxide. it is then refined to obtain pure tin.

(ii) SnO\(_{2(s)}\) + 2C\(_{(s)\) \(\implies\) Sn\(_{(l)}\) + 2CO\(_{(g)}\)

(iii) (I) Sn\(_{(s)}\) + O2\(_{(g)}\) \(\implies\) Sn\(_{2(s)}\)

(II) Sn\(_{(s)\) + 2Cl\(_{2(g)}\) \(\implies\) SnCl\(_{4}\)

Correct Answer: C. Product brand

Correct Answer: A. parliament and the courts