1

### NEET 2016 Phase 1

Equal moles of hydrogen and oxygen gases are placed in a container with a pin-hole through which both can escape. What fraction of the oxygen escapes in the time required for onehalf of the hydrogen to escape?
A
3/8
B
1/2
C
1/8
D
1/4

## Explanation

Let the number of moles of each gas = x

Fraction of hydrogen escaped = ${1 \over 2}x$

${{{r_{{O_2}}}} \over {{r_{{H_2}}}}} = \sqrt {{{{M_{{H_2}}}} \over {{M_{{O_2}}}}}}$

$\Rightarrow {{{n_{{O_2}}}/t} \over {{x \over 2}/t}} = \sqrt {{2 \over {32}}} = \sqrt {{1 \over {16}}} = {1 \over 4}$

$\Rightarrow {n_{{O_2}}} = {1 \over 8}x$

Then, fraction of oxygen escaped = ${1 \over 8}$
2

### AIPMT 2015

A gas such as carbon monoxide would be most likely to obey the ideal gas law at
A
low temperaures and high pressures
B
high temperatures and hgh pressures
C
low temperatures and low pressures
D
high temperature and low pressures.

## Explanation

Real gas shows ideal gas behaviour at high temperature and low pressure.
3

### NEET 2013

Maximum deviation from ideal gas is expected from
A
CH4(g)
B
NH3(g)
C
H2(g)
D
N2(g)

## Explanation

The compressibility factor is the term which is measured for a gas to study its deviation from the ideal behaviour. Compressibility factor,

$Z = {{PV} \over {nRT}}$

Greater is the difference in the value of Z from 1, greater is the deviation of the gas from ideal behaviour.

Among the given molecules, NH3 is easily liquefiable gas which deviates from ideal behaviour to the maximum extent.
4

### NEET 2013 (Karnataka)

What is the density of N2 gas 227oC and 5.00 atm. pressure? (R = 0.082 L atm K$-$1 mol$-$1)
A
1.40 g/mL
B
2.81 g/mL
C
3.41 g/mL
D
0.29 g/mL

## Explanation

PV = nRT

$\Rightarrow$ PV = ${W \over M}RT$

$\Rightarrow$ $P = {W \over M} \times {{RT} \over V}$

$\Rightarrow$$P = {{dRT} \over M}$   [Density = ${{Mass} \over {Volume}}$]

$\Rightarrow d = {{PM} \over {RT}} = {{5 \times 28} \over {0.0821 \times 500}} = 3.41\,g/ml$