Examine the statements and select the appropriate answer.

Statement I: A thermos flask is made of double-walled glass bottles.

Statement II: Metals are good conductors while gas and air are poor conductors of heat.

• Both the statements are individually true and Statement II is the correct explanation of Statement I

• Both the statements are individually true but Statement II is not the correct explanation of Statement I

• Statement I is true but Statement II is false

• Statement I is false but Statement II is true

272.

Examine the statements and select the appropriate answer.

Statement I: Bats can catch their prey in the darkness of night.

Statement II: Bats can produce and also detect ultrasound.

• Both the statements are individually true and Statement II is the correct explanation of Statement I

• Both the statements are individually true but Statement II is not the correct explanation of Statement I

• Statement I is true but Statement II is false

• Statement I is false but Statement II is true

A refracting telescope consists of

• one concave mirror and one convex lens

• two convex lenses of equal focal length

• two concave mirrors of different focal lengths

• two convex lenses of unequal focal lengths

Two similarly charged bodies are kept 5 cm apart in the air.
If the second body is shifted away from the first by
another 5 cm, their force of repulsion will be

• doubled

• halved

• quadrupled

• reduced to one-fourth

The main power supply in India is at 220 V, whereas that in the US is at 110 V. Which one among the following statements in this regard is correct?

• 110 V is safer but more expensive to maintain

• 110 V is safer and cheaper to maintain

• 110 V leads to lower power loss

• 110 V works better at higher latitudes

An object is in a uniform circular motion on a plane. Suppose that you measure its displacement from the centre along one direction, say, along the x-axis. Which one among the following graphs could represent this displacement (x)?

The penetrating power of X-rays can be increased by

• increasing the current in the filament

• decreasing the potential difference between the cathode and the anode

• decreasing the current in the filament

• increasing the potential difference between the cathode and the anode

The graph given above indicates a change in temperature (0) when heat (Q) was given to a substance. Which among the following parts of the graph correctly depict the latent heat of the substance?

• AB and BC

• BC and DE

• CD and DE

• DE and AB

When a solid object is immersed in water, there is a loss in its weight. This loss is

• equal to the weight of the water displaced

• less than the weight of the water displaced

• greater than the weight of the water displaced

• not related to the weight of the water displaced

Body A of mass 2 kg and another body B of mass 4 kg and of the same material are kept in the same sunshine for some interval of time. If the rise in temperature is equal for both the bodies, then which one among the following in this regard is correct?

• Heat absorbed by B is double because its mass is double

• Heat absorbed by A is double because its mass is half

• Heat absorbed by both A and B is equal because the quantity of heat absorbed does not depend upon mass

• Heat absorbed by B is four times than the heat absorbed by A because the quantity of heat absorbed is proportional to square of the mass