# How many molecules are present in one gram of hydrogen?

$\begin{array}{1 1}(a)\;6.02\times 10^{23}& (b)\;3.01\times 10^{23} \\(c)\;2.5\times 10^{23}&(d)\;1.5\times 10^{23}\end{array}$

Molecules in 1g $H_2=\large\frac{1}{2}$mole
$\Rightarrow \large\frac{1}{2}$$\times 6.02\times 10^{23}$
$\Rightarrow 3.01\times 10^{23}$
Hence (b) is the correct answer.