WAEC Past Questions and Answers - Page 3262

16,306.

At which position should an object be placed in front of a concave mirror in order to obtain an image which is of the same size as the object?

A.

at the centre of curvature

B.

at the principal focus

C.

between the pole and principal focus

D.

between the centre of curvature and principal focus

Correct answer is A

No explanation has been provided for this answer.

16,307.

Which of the following is true about import substitution? It

A.

Helps in increasing exportation

B.

Is meant to reduce exportation

C.

Enables a country to curtail importation

D.

Enables a country to improve on importation

Correct answer is C

Import substitution is a policy advocating for replacing foreign imports with domestic production. It is aimed at reducing the importation of foreign goods.

16,308.

The equation of a certain progressive transverse wave is y = 2 sin 2 \(\pi ( \frac{t}{0.01} - \frac{x}{30})\), where x and y are in cm and t in seconds. Calculate the period of the wave.

A.

0.001s

B.

0.010s

C.

10.000s

D.

100.000s

Correct answer is B

Compare: Y = 2 sin 2 \(\pi (\frac{t}{0.01} - \frac{x}{30})\)

with the wave equation,

y = A sin 2 \(\pi (\frac{t}{T} - \frac{x}{\lambda}\))

⇒ \(\frac{t}{T} = \frac{t}{0.01}\)

T = 0.010s

16,309.

When there is improvement in a country's terms of trade, it means that the country's

A.

Exports are cheaper relative to imports

B.

Imports are cheaper relative to exports

C.

Volume of imports has declined

D.

Volume of exports has declined

Correct answer is B

Terms of trade (TOT) represent the ratio between a country's export prices and its import prices. If a country's terms of trade improve, it means that for every unit of exports sold it can buy more units of imported goods. 

16,310.

When salt is dissolved in water, the freezing point of the water

A.

increases

B.

decreases

C.

remains the same

D.

increases and later decrease

Correct answer is B

The salt in the water (same for any other impurities) lowers the freezing point of the solution so that water freezes at a lower temperature.