Gases begin to conduct electricity at low pressure because

An ideal gas is enclosed in a cylinder at a pressure of $2 \, atm$ and a temperature of $300 \, K$. The mean time between two successive collisions is $6 \times 10^{-8} \, s$. If the pressure is doubled and the temperature is increased to $500 \, K$,the mean time between two successive collisions will be close to:

What is mean free path?

Two ideal gas thermometers $A$ and $B$ use oxygen and hydrogen respectively. The following observations are made:

Temperature	Pressure thermometer $A$	Pressure thermometer $B$
Triple-point of water	$1.250 \times 10^{5} \; Pa$	$0.200 \times 10^{5} \; Pa$
Normal melting point of sulphur	$1.797 \times 10^{5} \; Pa$	$0.287 \times 10^{5} \; Pa$

$(a)$ What is the absolute temperature of the normal melting point of sulphur as read by thermometers $A$ and $B$?
$(b)$ What do you think is the reason behind the slight difference in answers of thermometers $A$ and $B$? (The thermometers are not faulty). What further procedure is needed in the experiment to reduce the discrepancy between the two readings?

$A$ system consists of two types of gas molecules $A$ and $B$ having the same number density $2 \times 10^{25} \, /m^3$. The diameters of $A$ and $B$ are $10 \, \mathring{A}$ and $5 \, \mathring{A}$ respectively. They undergo collisions at room temperature. The ratio of the average distance covered by molecule $A$ to that of $B$ between two successive collisions is $..... \times 10^{-2}$.

The temperature below which a gas should be cooled,before it can be liquefied by pressure only,is termed as: