Explanation

(i) Coke, Coal, Carbon black, any of the charcoal and carbon fibers.

(ii) Graphite is a lubricant because of its layered crystalline structure which allows one layer to slide over one another while diamond has ;table and rigid crystal lattice.

(iii) Draw the diagram on the marking scheme.

(b)(I) Soil pollutant iomestic waste, polythene, pesticides, oil spillage, etc.

(II) Water pollutant — Factory waste, domestic waste etc.

(III)Air pollutant — Sulphur (IV) oxide, carbon (II) oxide, oxides of nitrogen and chlorofluorocarbon, etc.

(ii) The major use of SO\(_2\) in a chemical industry is in the manufacture of H\(_2\)SO\(_4\).

(c)(i) The intermolecular orces in petrol are weak and hence are easily broken for the molecules to escape.

(ii) The criteria are ponstant melting point, constant boiling point, its density, refractive index, etc.

(iii) Krypton is used in photography, etc.

(ii) Argon is used in gas-filled electric lamps.

(d)(i) I. Zinc tetraoxosulphate (VI) ; Zn\(_{(s)}\) + Cu\(^{2+}\)SO\(^{2-}_{4}\) --> Zn\(^{2+}\) + Cu\(_{(s)}\)

OR Zn\(_{(s)}\) + Cu\(^{2+}_{(aq)}\) --> Zn\(^{2+}_{(aq)}\) + Cu\(_{(s)}\)

IIl. A white precipitate is Formed

(ii) Na\(_2\)CO\(_{3(s)}\) + 2HNO\(_{3(aq)}\) ---> 2NaNO\(_{3(aq)}\) + CO\(_{2(s)}\) + H\(_2\)O\(_{(l)}\)

Molar mass of Na\(_2\)CO\(_3\) = 23 + 2 + 12 + 16 x 2 = 106.

106 of Na\(_2\)CO\(_3\) produces 22.4dm\(^3\) of CO\(_2\) at s.t.p.

5.3g of Na\(_2\)CO\(_3\) will produce \(\frac{5.3 \times 22.4}{106}\)

= 1.12 dm\(^3\)

Correct Answer: A. 8.25

Explanation

Mean \(\bar{x}\) = \(\frac{3 + 7 + 6 + 2 + 8 + 5 + 9 + 1 + 4 + 10}{10} \)

= \(\frac{55}{10} = 5.50\)

Variance = \(\frac{\sum (x - \bar{x})^{2}}{n}\)

= \(\frac{82.5}{10}\)

= 8.25

Explanation

(a) Advantages of courier services:

(i) It delivers safely and quickly.

(ii) It collects and delivers goods personally.

(iii) It delivers goods to all part of the country

(iv) It provides 24 hours service daily.

(v) Misplacement of parcels through courier services is minimal.

(b) Communication services rendered by the post office:

(i) Express delivery

(ii) Post Restante

(iii) Recorded delivery

(iv) Sales of stamps.

(v) Business Reply Service.

(vi) Registered mail

(vii) Parcel post

(viii) Ordinary mail.

(ix) P. 0. Box / P. M. B

Explanations:

(i)Express delivery:It is fast and quick means of sending letters and parcels through the post office. It attracts extra charge. Arrangement is made to deliver the letter to the addressee when it reaches its destination.

(ii)Post restante: It is a service rendered to tourists who have no fixed address. This allows the tourist to receive his mails while on transit.

(iii) Recorded delivery:It is a means of sending important documents through post office. Certificate of posting is issued to sender. The person to whom it is sent signs as evidence of receipt. It attracts extra charge.

(iv)Business reply services:This facilities is rendered to the specific businessman who has applied in advance. It enables the public to reply to business advertisements without paying for postage stamps. The post office issues license to firm that requires this service. The business or the license pays the charge in advance.

(v) Sale of stamps:The post office sells stamps to people who wish to send letters, parcels, etc through post. Stamps are adhesives in different denomination that are affixed to whatever people want to send through the post office. Each letter or parcel must bear the correct charge of postage stamp.

(iv)Parcel Post:Parcel sent through the post are weighed and charged accordingly. They would go by ordinary mail or be registered if they contained valuable items. When parcels are registered, their owners can claim compensation if there is a loss.

(vii)Ordinary mail:This costs less to post but has a weight limit. When an ordinary mail weights more than extra charge in postage is paid. In the event of loss, the post office does not pay any compensation to the sender. Valuable items are not sent through ordinary mail. Ordinary mail takes a longer time to get to its destination.

(viii)Registered mail/post: This is a safe way of sending valuable articles/items through the post. It costs more than an ordinary mail. A registered mail is not put into a posting box. It is over to an official of the post office. A receipt is issued to cover a registered mail. In the event of loss the sender is entitled to compensation when he provides the receipt of posting.

(ix)P. O. BOX / P. M. B:Provision of these allow owners to personally collect their letter at convenient times. The boxes and bags are locked at the post office in order to ensure security and privacy of letters. An annual rental fee is charged.

Correct Answer: C. it has a large surface area to volume ratio.

Explanation

(i) Costly to run: The constitution operates a presidential system of government with comprehensive duplication of political functions, thereby making it too expensive and costly to run.

(ii) Abuse of impeachment clause: The impeachment clause as stipulated in the constitution could be abused by the lawmakers to victimise a political opponent.

(iii) Delay in implementation of programmes: Separation of powers could result in a delay in the implementation or carrying out of government programme. For example, the National Assembly can delay the approval of budget, ministerial and other appointments to be made by the president.

(iv) Refusal of the executive to honour the judgement of the supreme court: the executive can refuse to honour the judgement of the supreme court because of the sovereign immunity it has.

(v) Activities in government: Government activities could be brought to a standstill because of problems between the executive and legislative arms of government, especially when the ruling party does not have a majority seat in parliament.

(vi) Over- concentration of powers: Some critics have argued that the Executive president as both Head of State and Government has excessive powers concentrated in him, and this creates room for abuse of powers.

Correct Answer: D. maintaining high levels of soil nutrients reserves

Correct Answer: B. The change in form and structure during the life cycle of certain organisms

Explanation

Metamorphosis is commonly observed in certain animal groups, such as insects (e.g., butterflies, beetles) and amphibians (e.g., frogs, salamanders). It involves a dramatic change in body form and structure as an organism progresses through distinct stages of its life cycle. These stages may include egg, larval, pupal, and adult phases.

Correct Answer: D. demand for his products is completely elastic

Correct Answer: C. removal of weeds

Correct Answer: D. hostile

Explanation

amicable; characterized by friendliness and absence of discord.

hostile; showing or feeling opposition or dislike; unfriendly.