1.
Water has maximum density at............
Answer: Option 'C'
4 C
2.
An air bubble in water will act like a
Answer: Option 'B'
concave lens
3.
Quality of transmission depends upon
Answer: Option 'C'
Quality of transmission is governed both by nature of signal and nature of communication channel/medium.
4.
When an electric bulb breaks , there is an explosive sound. That is due to
Answer: Option 'C'
The inside of the bulb being a vacuum, the outside air rushes in when the bulb is broken. The vibrations of the rushing air molecules produce the sound.
5.
Quality of transmission depends upon
Answer: Option 'C'
Both (A) and (B)
Quality of transmission is governed both by nature of signal and nature of communication channel/medium.
6.
The image of an object formed on the retina of the eye is
Answer: Option 'C'
Although the image is inverted the mental interpretation of the effect on the retina is as though it is erect
7.
Erg cross Sec is the unit of
Answer: Option 'C'
Planck's constant
8.
A bucket of water is hung from a spring balance. A piece of iron is suspended in the water without touching the sides or touching the bottom of the bucket. The reading of the spring balance
Answer: Option 'B'
will increase
When the piece of iron is lowered into the water, the water level in the bucket increases. And so the pressure at the bottom of bucket also increases. Thus the total thrust at the botto also increases. Therefore the spring balance reading increases.
9.
Which of the following is not a vector quantity
Answer: Option 'A'
speed
10.
Two electric bulbs marked 25W – 220V and 100W – 220V are connected in series to a 440Vsupply. Which of the bulbs will fuse?
Answer: Option 'B'
Resistances of both the bulbs are R1=V^2/P1 = 220^2/25 R2 = V^2/P2 = 220^2/100 Hence R1gt ; R2R1gt ; R2 When connected in series, the voltages divide in them in the ratio of their resistances. The voltage of 440 V devides in such a way that voltage across 25 w bulb will be more than 220 V. Hence 25 w bulb will fuse.
11.
"Light years" is the unit of _____?
Answer: Option 'B'
Distance
12.
A solid ball of metal has a spherical cavity inside it. When the ball is heated the volume of the cavity will
Answer: Option 'B'
The metal ball can be considered to be made up of several layers of thinner ones. On heating each of these layers will increase in radius. As the inner most layer also increases its radius, the volume inside it i.e, the volume of the hollow portion will also increase.
13.
Radio waves sent out by a radio stations are reflected by
Answer: Option 'D'
This is a layer of atmosphere about 60 to 70 km above the earth and extends to about 400km. It contains ionised particles which can reflect radio waves making radio communication round the world possible.
14.
Which of the following is a scalar quantity
Answer: Option 'D'
work
15.
Skating on ice is possible because
Answer: Option 'A'
the pressure on the ice due to skate melts the ice by lowering its melting point forming a thin film of water
Here is a case of lowering of melting point of ice with increase of pres
16.
Rolling friction is caused by ____ from the following?
Answer: Option 'A'
Rolling friction or rolling drag is the force resisting the motion when a body rolls on a surface. It is mainly caused by non-elastic effects, that is, not all the energy needed for deformation of the wheel, roadbed, etc... is recovered when the pressure is removed. Another cause of rolling resistance lies in the slippage between the wheel and the surface, which dissipates energy.
17.
A nuclear reactor is said to have become 'critical' when
Answer: Option 'D'
it is ready to produce controlled energy
To produce controlled energy i.e energy at a controlled or steady rate, the number of fissions per second must be controlled and maintained at that rate. Excess neutrons should be absorbed by control roads like cadmium.
18.
Earlist thermometerr was developed by
Answer: Option 'B'
Galileo
19.
When one enters a dark room after being in bright light one is not able to see anything clearly for a while because
Answer: Option 'C'
The size of the pupil of the automatically adjusts itself according to the intensity of light passing through it; if the intensity is more, the size is less, if less, it is more. So in our case the pupil should dilate i.e , increase in size to be able to see in the dark. This switchover takes some time. But here the entry into the dark room is immediate. So the eye has no time to adjust itself and hence is not able to see at all for a while.
20.
What is unit of Astronomical distance?
Answer: Option 'A'
angstrom is used to measure wave length, weber is used to measure Magnetic flux, lux is used to measure Intensity of illumination.