Correct Answer: C. 2m; 0.50Hz

Explanation

For the 4th harmonic, \(L = 2\lambda\)

\(4m = 2\lambda \implies \lambda = \frac{4m}{2}\)

=\(2m\)

Recall, \(v = f\lambda\)

\(1 = f \times 2 \implies f = \frac{1}{2}\)

= 0.50Hz

Explanation

(a)(i) Letter of enquiry:

(i) Sent by the buyer to the seller to find out about the availability of goods their prices and the terms of payment.

(ii) It informs the seller of the goods required, the quantity, the time and the terms of delivery.

(ii) Invoice:

(i) It is document showing details of goods sold.

(ii) It serves as a receipt.

(iii) It is used to write up the purchases I sales journals.

(iii) Advice note:

(i) Sent to the buyer to inform him about the dispatch of the goods.

(ii) Informs the buyer of the quantity and type of goods, means of transport used and the expected date of arrival.

(iv) Credit note;

(i) Sent by the seller to correct an overcharge on an invoice.

(ii) Sent when the buyer has returned some faulty goods to the seller.

(iii) Sent when the seller has decided to give an allowance to the buyer.

(v) Statement of account:

(i) It enables the customer of a firm to have a thorough check of what he has purchased.

(ii) It also gives the customer an idea as to his financial standing at a given period.

(iii) The information in it is used by bank customer to prepare a bank reconciliation statement.

(vi) Debit note:

(i) Sent to the buyer when goods sold to him have been under-charged on an invoice.

(ii) It informs the buyer that his account has been debited.

(vii) Advantages of Automatic Vending:

(i) The sale is automatic, so it saves the cost of labour.

(ii) it operates/ opens for 24 hours: no time limit.

(iii) It is convenient to operate.

(b) Disadvantages of Automatic Vending:

(ii) Limited to a range of goods.

(ii) Subject to availability of goods.

(iii) Machines can be vandalized.

(iv) Machines can be faulty.

(v) It is expensive to operate/maintain.

Correct Answer: D. inhibiting the action of digestive enzymes

Correct Answer: C. Rift valley

Correct Answer: D. Severe Acute Respiratory Syndrome

Explanation

(i) General formula for alkanoic acid is C\(_n\)H\(_{2n + 1}\) COOH. Two chemical properties of ethanoic acid

- Reacts with alkanols to form ethanoates or alkanoates or esters (esterification)

- Reacts with trioxocarbonate (IV) or hydrogen trioxocarbonate (IV) to produce carbon (IV) oxide

- Reacts with sodium hydroxide or potassium hydroxide to form sodium or potassium ethanoate.

(b)(i) Propene will decolorize acidified KMnO\(_4\) solution

(ii) Propene can easily be polymerised

(iii) Butane is an isomer of methylpropane

(iv) Propene can be obtained from alkanol by dehydration.

Correct Answer: D. provision of portable drinking water

Correct Answer: A. dot map

Correct Answer: A. common ownership of the means of production

Correct Answer: A. 1/6