What is the number of molecules in $1 \, litre$ of an ideal gas at $S.T.P.$?

$A$ perfect gas at $27^{\circ}C$ is heated at constant pressure so as to double its volume. The final temperature of the gas will be,close to ...... $^{\circ}C$

$A$ gas is heated through $1\,^{\circ}C$ in a closed vessel. Its pressure is increased by $0.5\%$. The initial temperature of the gas is ...... $^{\circ}C$.

For Boyle's law to hold, the gas should be:

When the pressure of a gas is increased by $0.4\%$,its temperature increases by $1\,^{\circ}\text{C}$. What is the initial temperature of the gas?

The figure shows two flasks connected to each other. The volume of flask $1$ is twice that of flask $2$. The system is filled with an ideal gas at temperatures $100\,K$ and $200\,K$ respectively. If the mass of the gas in flask $1$ is $m$,what is the mass of the gas in flask $2$?