NEET

A monatomic ideal gas expands at constant pressure, with heat Q supplied. The fraction of Q which goes as work done by the gas is

1
²⁄₃
³⁄₅
²⁄₅

Solution

Q = nC_pΔT and W = PΔV = nRΔT.

For monatomic gas,C_p = ^5R⁄₂ ⇒^W⁄_Q = ²⁄₅

The pressure inside a tyre is 4 times that of atmosphere. If the tyre bursts suddenly at temperature 300 K, what will be the new temperature?

300 (4)^7/2
300 (4)^2/7
300 (2)^7/2
300 (4)^-2/7

Solution

One mole of an ideal monoatomic gas is heated at a constant pressure of one atmosphere from 0ºC to 100ºC. Then the work done by the gas is

6.56 joule
8.32 × 10² joule
12.48 × 10² joule
20.8 × 10² joule

Solution

An ideal refrigerator has a freezer at a temperature of 13ºC.The coefficient of performance of the engine is 5. The temperature of the air (to which heat is rejected) is

320ºC
39ºC
325 K
325ºC

Solution

1 gm of water at a pressure of 1.01 × 10⁵ Pa is converted intosteam without any change of temperature. The volume of 1g of steam is 1671 cc and the latent heat of evaporation is 540 cal. The change in internal energy due to evaporation of 1 gm of water is

≈ 167 cal
≈ 500 cal
540 cal
581 cal

Solution

The temperature at which speed of sound in air becomes double of its value at 27° C is

54°C
327°C
927°C
None of these

Solution

Three moles of an ideal gas kept at a constant temperature at 300 K are compressed from a volume of 4 litre to 1 litre.The work done in the process is

– 10368 J
–110368 J
12000 J
120368 J

Solution

An ideal gas heat engine operates in Carnot cycle between 227°C and 127°C. It absorbs 6 × 10⁴ cals of heat at higher temperature. Amount of heat converted to work is