1

### AIPMT 2008

If a gas expands at constant temperature, it indicates that
A
kinetic energy of molecules remains the same
B
number of the molecules of gas increases
C
kinetic energy of molecules decreases
D
pressure of the gas increases.

## Explanation

Kinetic energy of a gas is expressed as

K.E = ${3 \over 2}nRT$

Thus, on expansion of fixed amount of gas at constant temperature the kinetic energy remains constant.
2

### AIPMT 2002

Van der Waal's real gas, acts as an ideal gas, at which conditions?
A
High temperature, low pressure
B
Low temperature, high pressure
C
High temperature, high pressure
D
Low temperature, low pressure

## Explanation

At higher temperature and low pressure real gas acts as an ideal gas.
3

### AIPMT 2001

The beans are cooked earlier in pressure cooker because
A
boiling point increases with increasing pressure
B
boiling point decreases with increasing pressure
C
extra pressure of pressure cooker softens the beans
D
internal energy is not lost while coocking in pressure cooker.

## Explanation

When water pressure increases in the pressure cooker, water boils at lower temperature and the beans in pressure cooker are cooked earlier.
4

### AIPMT 2000

Which of the following expressions correctly represents the relationship between the average molar kinetic energy, KE, of CO and N2 molecules at the same temperature ?
A
KECO = KEN2
B
KECO > KEN2
C
KECO < KEN2
D
cannot be predicted unless volumes of the gases are given

## Explanation

Average molar kinetic energy = ${3 \over 2}nRT$

As temperature is same hence average kinetic energy of CO and N2 will be same.