# Physics 2010 | Study Mode

Question 11
A
12 kgm-3
B
10 kgm-3
C
8 kgm-3
D
5 kgm-3
##### Explanation
Density, p = (mass)/volume (m)/(v)
0.4 = (m)/20
m = 20 x 0.4 = 8 kg
V = (m)/p = (8)/0.8 = 10 m3
N:B the units for the options are wrong

Question 12
A
x-rays
B
light energy
C
infrared rays
D
solar energy
##### Explanation
Inform falling on the skin causes the skin causes the sensation of warmth. since the objects are hot, the correct option is informed.

Question 13
A
the level of water goes up
B
the water in the glass outflows
C
the level of water remains unchanged
D
the level of water drops
##### Explanation
Due to anomalous expansion of water at temperature range (0 - 4)c, when a given mass of water turns into ice, its volume will increase, while the mass remains constant. Thus, when a given volum of ice melts, the volume of water formed will be less than the volume of ice. Hence, the level of water in the container will drop.

Question 14
A
hail
B
dew
C
fog
D
mist
##### Explanation
Dew point is the temperature at which the water vapour present in air is just sufficient to saturate it. Dew is formed when air is cooled below its dew point

Question 15
A
a dynamic equilibrium exists between liquid molecules and the vapour molecules
B
a dynamic aquilibrium exists such that more molecules return to the liquid than are living it
C
the temperature of the vapour varies
D
the vapour pressure is atmospheric
##### Explanation
A saturated vapour is one which is in dynamic equilibrium with its own liquid; that is as many go from the liquid to the vapour state every second return back to liquid.

Question 16
A
2.49 x 104 Nm-2
B
2.24 x 104 Nm-2
C
2.49 x 105 Nm-1
D
2.24 x 105 Nm-1
##### Explanation
T = 27 + 273 = 300 K, volume, V = 10-2 m3 molar gass constant, R = 8.3 Jmol- 1k - 1 number of mole, n = 1
PV = NRT
i.e P = (NRT)/V = (1 x 8.3 x 300)/10-2
= 2.49 x 105 Nm-1

Question 17
A
nature of surface
B
density
C
surface area
D
temperature
##### Explanation
Radiation depends on nature of the surface area and temperature. It is independent of density.

Question 18
A
1.2 s
B
1.0 s
C
0.5 s
D
0.1 s
##### Explanation
V = f
f = (v)/ = (420)/42 = 10 HZ
Period, T = (1)/F = (1)/10 = 0.1 secs

Question 19
A
the wavelength of sound becomes greater in the bottle
B
sound cannot pass through the bottle
C
sound needs a material medium
D
sound can pass through a vacuum
##### Explanation
Sound wave requires a material medium for its propagation. so when air is being pumped out the density of the medium is being reduced and the sound dies down. when all the air has been pumped out of the glass, no sound will be heard, as sound sound cannot travel through vacuum

Question 20
A
diffraction of sound
B
refraction of sound
C
superposition
D
reveraberation
##### Explanation
The lengthening effect of sound is known as reverberation.

Try this quiz in in E-test/CBT Mode
switch to