WAEC Past Questions and Answers - Page 3320

16,596.

In the day time, it is possible to see under shady areas such as under a tree because light has undergone

A.

internal reflection

B.

refraction

C.

diffraction

D.

diffuse reflection

Correct answer is D

No explanation has been provided for this answer.

16,597.

Light is considered as a transverse wave because it travels

A.

through material without causing disturbance of the medium

B.

through space with constant speed

C.

in a direction parallel to the plane containing the electric and magnetic fields

D.

in a direction perpendicular to the plane containing the electric and magnetic fields

Correct answer is D

No explanation has been provided for this answer.

16,598.

It takes a shorter time for a liquid to boil at the top of a mountain than at the base because at the top, the

A.

temperature is higher

B.

pressure is lower

C.

humidity is higher

D.

temperature is constant

Correct answer is B

No explanation has been provided for this answer.

16,599.

The working principle of a pressure cooker is based on the

A.

increase in the volume of steam inside it

B.

complete trapping of heat inside it

C.

increase in the pressure of the pot

D.

decrease in the pressure of the pot

Correct answer is C

No explanation has been provided for this answer.

16,600.

Water of mass 1.5kg is heated from from 30oC to 80oC using an electric kettle which is rated 5A, 230V. Calculate the time taken to reach the final destination [specific heat capacity of water 4200Jkg-1K-1]

A.

4.57 minutes

B.

5.02 minutes

C.

7.30 minutes

D.

10.04 minutes

Correct answer is A

t = \(\frac{MC\theta}{2} = \frac{1.5 \times 4200 \times 50}{5 \times 230}\)

= 273.91s or 4.57 mins