The mass of $112 \ cm^3$ of $CH_4$ gas at $STP$ is ............. $g$.

The atomic weights of two elements $A$ and $B$ are $40$ and $80$ respectively. If $x \ g$ of $A$ contains $y$ atoms,how many atoms are present in $2x \ g$ of $B$?

How many moles of magnesium phosphate,$Mg_{3}(PO_{4})_{2}$ will contain $0.25 \ mol$ of oxygen atoms?

Consider two sealed jars of equal volume. One contains $2 \ g$ of hydrogen at $200 \ K$ and the other contains $28 \ g$ of nitrogen at $400 \ K$. The gases in the two jars will have

How many atoms are contained in $5.6 \ L$ of oxygen gas at $STP$?

How many molecules are present in $22400 \ cm^3$ of a gas at $STP$?