# 1994 - JAMB Physics Past Questions and Answers - page 2

11

Which of these statements are TRUE of pressure in liquids? i. pressure acts equally in all direction. ii. pressure decreases with depth. iii. pressure at the same level of a liquid is the same. iv pressure is dependent on the cross-sectional area of the barometer tube

A

i, iii only

B

i, ii, iii only

C

i, iii, and iv only

D

i, ii, iii and iv

**correct option:**a

12

The mass of a specific gravity bottle is 15.2g when it is empty. it is 24.8g when filled with kerosene and 27.2g when filled with distilled water. Calculate the relative density of kerosene

A

1.25

B

1.10

C

0.90

D

0.80

**correct option:**d

Masses of kerosene = 24.8 - 15.2

= 9.6

mass of H

= 12

R.d = \(\frac{9.6}{12}\) = 0.8

Users' Answers & Comments= 9.6

mass of H

_{2}O = 27.2 - 15.2= 12

R.d = \(\frac{9.6}{12}\) = 0.8

13

If a solid X floats in liquids P of relative density 2.0 and in liquid Q of relative density 1.5, it can be inferred that the

A

weight of P displaced is greater than that of Q

B

weight of P displaced is less than that of Q

C

volume of P displaced is greater than that of Q

D

volume of P displaced is less than that of Q

**correct option:**a

R.d \(\alpha\) weight of liquid displaced

\(\frac{\text {R.d of P}}{\text {R.d of Q}}\) = \(\frac{\text{weight of p displaced}}{\text{weight of Q displaced}}\)

\(\frac{2}{1.5}\) = \(\frac{\text {weight of p displaced}}{\text {weight of Q displaced}}\)

Users' Answers & Comments\(\frac{\text {R.d of P}}{\text {R.d of Q}}\) = \(\frac{\text{weight of p displaced}}{\text{weight of Q displaced}}\)

\(\frac{2}{1.5}\) = \(\frac{\text {weight of p displaced}}{\text {weight of Q displaced}}\)

14

The melting point of naphthalene is 78

^{o}C. What is this temperature in kelvinA

100k

B

351k

C

378k

D

444k

15

A Motor Tyre is inflated to pressure of 2.0 x 10

^{5}Nm^{-2}when the temperature of air is 27^{o}C. What will be the pressure in it at 87^{o}C assuming that the volume of the Tyre does not change?A

2.6 x 10

^{5}Nm^{-2}B

2.4 x 10

^{5}Nm^{-2}C

2.2 x 10

^{5}Nm^{-2}D

1.3 x 10

^{5}Nm^{-2}**correct option:**b

\(\frac{p_1}{T_1}\) = \(\frac{p_2}{T_2}\)

\(\frac{2 \times 10^5}{27 + 273}\) = \(\frac{p_2}{87 + 273}\)

P

Users' Answers & Comments\(\frac{2 \times 10^5}{27 + 273}\) = \(\frac{p_2}{87 + 273}\)

P

_{2}= 2.4 x 10^{5}Nm^{-2}16

When 100g of liquids L

_{1}at 78^{o}C was mixed with Xg of liquid L_{2}at 50^{o}C, the final temperature was 60^{o}C. Given that the specific heat capacity of L_{2}is half that of L_{1}, find xA

50g

B

100g

C

150g

D

200g

**correct option:**c

Heat lost by L

cL

100 x 2cL

= xg x cL

xg = 150g

Users' Answers & Comments_{1}= heat gained by L_{2}cL

_{1}= 2cL_{2}100 x 2cL

_{2}x (78 - 60)= xg x cL

_{2}x (60 - 50)xg = 150g

17

Heat is supplied to a test tube containing 100g of ice at its melting point. The ice melts completely in 1 min.What is the power rating of the source of heat? [Latent heat of fusion of ice = 336Jg

^{-1}]A

336W

B

450W

C

560W

D

600W

18

If a room is saturated with water vapour, the temperature of the room must be

A

at 0

^{o}CB

above the dew point

C

at 100

^{o}CD

below or at the dew point

**correct option:**d

19

Two similar kettles containing equal masses of boiling water are placed on a table. If the surface of one is highly polished and the surface of the other is covered with soot, Which of the following observations is correct

A

The two kettles will cool down at the same rate

B

the polished kettle cools down more quickly by conduction

C

the kettle covered with soot cools down more quickly because it is a good radiator

D

the kettle covered with soot cools down more quickly by the process of heat convection

**correct option:**c

20

The equation of transverse wave traveling along a string is given by Y = 0.3 sin(0.5x - 50t) where Y and X are in cm and t is in seconds.Find the maximum displacement of the particles from the equilibrium position

A

50.0cm

B

2.5 cm

C

0.5cm

D

0.3cm

**correct option:**d

Y = 0.3 sin(0.5x - 50t) compare with,

y = A sin(kx - wt)

A = 0.3m

Users' Answers & Commentsy = A sin(kx - wt)

A = 0.3m