JAMB Physics Past Questions & Answers - Page 232

1,156.

Water shows anomalous behaviour.

A.

below 0oC

B.

between 0oC and 4oC

C.

at exactly 4oC

D.

between 4oC and 100oC

E.

above 100oC

Correct answer is B

No explanation has been provided for this answer.

1,157.

In a gas experiment, the pressure of the gas is plotted against the reciprocal of the volume of the gas at a constant temperature. the unit of the slope of the resulting curve is

A.

force

B.

force/m

C.

work

D.

force/m3

E.

energy/m3

Correct answer is C

slope = pressure \(\div\) \(\frac{1}{volume}\)

= \(\frac{N}{m^3}\) x \(\frac{m^3}{1}\)

= Nm = work

1,158.

A quantity of gas occupies a certain volume when the temperature is -73oC and the pressure is 1.5 atmospheres. If the pressure is increased to 4.5 atmospheres and the volume is halved at the same time, what will be the new temperature of the gas?

A.

573oC

B.

327oC

C.

300oC

D.

110oC

E.

27oC

Correct answer is E

General Gas Law:

\(\frac{P_1 V_1}{T_1}\) = \(\frac{P_2 V_2}{T_2}\)

where T\(_1\) = -73 + 273 = 200k,      T\(_2\) = ?,

V\(_1\) = 1,         V\(_2\) = \(\frac{1}{2V}\),

P\(_1\) = 1.5,      P\(_2\) = 4.5

T\(_2\) = \(\frac{P_2 V_2 T_1}{P_1 V_1}\)

T\(_2\) = \(\frac{4.5 * 1/2 * 200}{1.5 X 1}\)

T\(_2\) → 300k or 27ºC
 

1,160.

A thin aluminum plate has a surface area of 1500m at 20oC. What will be its surface area when it is cooled to -20oC? (Take the linear expansivity of aluminum to be 2.5 x 10-5k-1).

A.

1.503m2

B.

1.500m2

C.

1.498m2

D.

1.497m2

E.

1.490m2

Correct answer is C

\(\beta\) = A2 - A1

2 X 10-5 x 2.5 = \(\frac{A_2 \times 1.5}{1.5 \times (-20 -20)}\)

A2 = 1.498m2