An ideal gas at constant temperature and pressure expands,then its

The following graph shows a system containing $1 \ mole$ of gas undergoing various steps. When it moves from $z$ to $x$, the type of process is:

At a given temperature,the density of gas $x$ is twice the density of gas $y$. If the molar mass of $y$ is three times the molar mass of $x$,find the ratio of their pressures $(P_x/P_y)$.

If $10^{-4} \ dm^3$ of water is introduced into a $1.0 \ dm^3$ flask at $300 \ K,$ how many moles of water are in the vapour phase when equilibrium is established? (Given: Vapour pressure of $H_2O$ at $300 \ K$ is $3170 \ Pa;$ $R = 8.314 \ J \ K^{-1} \ mol^{-1}$)

Match the laws given in List-$I$ with their mathematical forms given in List-$II$.

List-$I$	List-$II$
$(1)$ Boyle's Law	$(A)$ $p \propto T$
$(2)$ Charles's Law	$(B)$ $V \propto n$
$(3)$ Gay-Lussac's Law	$(C)$ $p \propto \frac{1}{V}$
$(4)$ Avogadro's Law	$(D)$ $pV = nRT$
$(5)$ Ideal Gas Equation	$(E)$ $V = k_2T$

When $2 \ g$ of a gaseous substance $A$ is introduced into an initially evacuated flask at $25^{\circ} C$,the pressure is found to be $1 \ atm$. $3 \ g$ of another gaseous substance $B$ is added to it at the same temperature and pressure. The final pressure is found to be $1.5 \ atm$. Assuming ideal gas behaviour,the ratio of molar masses of $A$ and $B$ is: