In an experiment during the analysis of a carbon compound,$145 \ L$ of $H_2$ was collected at $760 \ mm \ Hg$ pressure and $27 \ ^oC$ temperature. The mass of $H_2$ is nearly $....... \ g$.

$A$ closed tank has two compartments $A$ and $B$,both filled with oxygen (assumed to be ideal gas). The partition separating the two compartments is fixed and is a perfect heat insulator (Figure $1$). If the old partition is replaced by a new partition which can slide and conduct heat but does $NOT$ allow the gas to leak across (Figure $2$),the volume (in $m^3$) of the compartment $A$ after the system attains equilibrium is. . . . . . . .

Which of the following statements is false?

At what new pressure will $100 \ mL$ of a gas at a pressure of $720 \ mm$ occupy a volume of $84 \ mL$,keeping the temperature constant (in $mm$)?

At $0^{\circ}C$,the density of a certain oxide of a gas at $2 \ bar$ is the same as that of dinitrogen at $5 \ bar$. What is the molecular mass of the oxide?

$4 \ g$ of an ideal gas occupies $5.6035 \ L$ of volume at $546 \ K$ and $2 \ atm$ pressure. What is its molecular weight?