TEST SERIES - 60 (II)

A piece of blue glass heated to a high temperature and piece of red glass at room temperature are taken inside dimly-lit room. Then,

• The blue piece will look blue and the red piece will red as usual

• Both the pieces will look equally red

• The blue piece will look brighter red as compared to the red piece

• Both the pieces will look red but the blue piece will be dimmer

Which of the following statements are true regarding heat? 1. Heat is a form of energy. 2. Heat can be reflected by mirror. 3. Heat is an electromagnetic radiation. 4. Heat cannot pass through vacuum. Select the correct answer from the codes given below:

• 1, 2 and 3

• 2, 3 and 4

• 1, 2 and 4

• 1, 3 and 4

When an ideal gas under goes an isothermal expansion, the pressure of the gas in the enclosure falls. This is due to

• Decreased in the change of momentum per collision

• Decrease in the frequency of collision

• Decrease in the frequency of collision and the change of momentum per collision

• Decrease in neither the frequency of collision nor the change of momentum per collision

Which of the following statement (s) is/are true about thermal radiations? 1. Thermal radiations are electromagnetic waves. 2. All bodies emit thermal radiations at all temperature. 3. Thermal radiations are reflected from mirror. 4. Thermal radiations of all wavelengths travel in free space with same velocity. Choose the correct answer

• 1, 2 and 3

• 2, 3 and 4

• 3 and 4

• All of them

In a pressure cooker the cooking is fast because

• The boiling point of water is raised by the increased pressure inside the cooker

• The boiling point of water is lowered by the increased pressure

• More steam is available to cook the food at 1000°C

• None of the above

Which of the following statement (s) is/are true about thermal radiations? 1. Thermal radiations are electromagnetic waves. 2. All bodies emit thermal radiations at all temperature. 3. Thermal radiations are reflected from mirror. 4. Thermal radiations of all wavelengths travel in free space with same velocity. Choose the correct answer

• 1, 2 and 3

• 2, 3 and 4

• 3 and 4

• All of them

A cooking pot should have

• High specific heat and low conductivity

• High specific heat and high conductivity

• Low specific heat and low conductivity

• Low specific heat and high conductivity

A piece of glass is heated to high temperature and then allowed to cool. If it cracks, a possible reason for this is the following property of glass

• Low thermal conductivity

• High thermal conductivity

• High specific heat

• Low specific heat

A piece of metal and a piece of wood are kept at temperature of 45°C on touching the two of them with hand

• The two will appear equally hot

• The piece of wood will appear hotter than the piece of metal

• The piece of metal will appear hotter than the piece of wood

• The distinction in the hotness will not be possible

A solid sphere of radius R and a hollow sphere of inner radius R/2 and outer radius R, made of copper, are heated to the same temperature and are allowed to cool in the same environment. Then,

• Hollow sphere cools faster

• Both the spheres attain room temperature at the same time

• Solid sphere cools faster

• None of the above