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JAMB Physics Past Questions & Answers - Page 197

981.

A pressure cooker saves both time and fuel in cooking because inside the cooker, the

A.

boiling point of water is raised

B.

pressure is constant

C.

heat is completely trapped

D.

temperature is evenly distributed

E.

volume of steam varies

Correct answer is A

When atmospheric pressure increases, the boiling point becomes higher, and when atmospheric pressure decreases (as it does when elevation increases), the boiling point becomes lower.

982.

The water at the bottom of a waterfall is slightly warmer than that at the top because part of the

A.

potential energy raises the water temperature

B.

water absorbs latent heat from the atmosphere

C.

kinetic energy is changed into internal energy

D.

dropping mass of water increases the heat capacity

E.

A and C above

Correct answer is C

No explanation has been provided for this answer.

983.

Which of the following does NOT cause a reduction of the surface tension of water?

A.

soap solution

B.

detergent

C.

alcohol

D.

camphor

E.

grease

Correct answer is E

No explanation has been provided for this answer.

984.

The motion of the moving skin of a talking drum can rightly be described as

A.

translational

B.

random

C.

rotational

D.

oscillatory

E.

transitory

Correct answer is D

No explanation has been provided for this answer.

985.

A given quantity of heat increases the temperature of 150grams of water from 9oC to 15oC and increases the temperature of oil of 100grams from 9oC to 25oC. The ratio of the specific heat of oil to that of water is

A.

0.36

B.

0.46

C.

0.56

D.

0.76

E.

0.86

Correct answer is C

Heat lost = heat gained

moCoθo = mwCwθw

100 x Co x (25 - 9) = 150 x Cw x (15 - 9)

CwCw = 0.56