If the pressure of a gas contained in a closed vessel is increased by $0.4\%$ when heated by $1\,^{\circ}C$,the initial temperature must be

$A$ metre-long narrow bore held horizontally (and closed at one end) contains a $76 \; cm$ long mercury thread,which traps a $15 \; cm$ column of air. What happens if the tube is held vertically with the open end at the bottom?

An ideal gas initially at pressure $1 \, bar$ is being compressed from $30 \, m^{3}$ to $10 \, m^{3}$ volume and its temperature decreases from $320 \, K$ to $280 \, K$. Find the final pressure of the gas (in $bar$).

The air density at Mount Everest is less than that at the sea level. It is found by mountaineers that for one trip lasting a few hours,the extra oxygen needed by them corresponds to $30,000 \, cc$ at sea level (pressure $1 \, atm$,temperature $27^{\circ}C$). Assuming that the temperature around Mount Everest is $-73^{\circ}C$ and that the oxygen cylinder has a capacity of $5.2 \, L$,the pressure at which $O_2$ must be filled (at site) in the cylinder is .... $atm$.

At $0\,^{\circ}\text{C}$,the value of the density of a fixed mass of an ideal gas divided by its pressure is $x$. At $100\,^{\circ}\text{C}$,this value will be

Two vessels separately contain two ideal gases $A$ and $B$ at the same temperature. The pressure of $A$ is twice that of $B$. Under these conditions,the density of $A$ is found to be $1.5$ times the density of $B$. The ratio of the molecular weights of $A$ and $B$ is: