WAEC Past Questions and Answers - Page 3604

18,016.

If the cubic expansivity of brass between 27oC and 100oC is 5.7 x 10-5K-1, What is its linear expansivity?

A.

2.85 x 10-5K-1

B.

1.90 x 10-5K-1

C.

1.86 x 10-5K-1

D.

1.70 x 10-5K-1

E.

1.63 x 10-5K-1

Correct answer is B

\(\alpha\) = \(\frac{\Delta}{3} = \frac{5.7 \times 10^{-5}}{3}\)

= 1.90 x 10-5K-1

18,017.

The average kinetic energy of the molecules of a perfect gas is directly proportional to the

A.

pressure exerted by the gas

B.

volume of the gas molecule

C.

kelvin temperature of the gas

D.

volume of the gas container

E.

celcius temperature of the gas

Correct answer is C

The average kinetic energy of the molecules of a perfect gas is directly proportional to the Absolute temperature that is the temperature measured using the kelvin scale.

18,018.

The lower and upper fixed points of a mecury-in-glass thermometer are marked Y and 180mm respectively. On a particular the mecury meniscus in the thermometer rises to 45mm. If the corresponding reading on a scale is 10o, calculate the value of Y.

A.

4mm

B.

18mm

C.

30mm

D.

135mm

E.

450mm

Correct answer is C

by interpolation,

\(\frac{100 - 0}{10- 0} = \frac{180 - y}{45 - y}\)

\(\frac{100}{10} = \frac{180 -y}{45 - y }\)

450 - 10y = 180 - y 

- 9y = - 270 

y = 30mm

 

18,019.

An object is heated from 30°C to 57°C. The increase in its temperature on the Kelvin scale is

A.

17k

B.

27k

C.

81k

D.

246k

E.

300k

Correct answer is B

30°C + 273 = 303K

57°C + 273 = 330K

∆T = 330K - 303K

→ 27K

18,020.

The earth is not a perfect sphere because its equatorial axis is longer than the polar axis. where on the earth's surface would an object have its greatest weight?

A.

half way between the equator and the north pole

B.

near the equator

C.

half way between the equator and the south pole

D.

at either pole

E.

at the equator

Correct answer is C

No explanation has been provided for this answer.