$\begin{array}{1 1} \text{(a) 22.4 litre at 1 atm and 250C} \\ (b)\;6.02 \times 10^{23} \;atoms\; of\; hydrogen\; and \;6.02 \times 10^{23}\; atoms\; of\; oxygen \\ (c) \;18 \;g \\ (d)\; 1\; gal \end{array} $
