Answer:
There are 1.5055X10^23 molecules present in 0.25 moles of Hydrogen gas.
Explanation:
We know,
1 mole of Hydrogen gas contains 6.022X10^23 molecules
∴ 0.25 moles of Hydrogen contains {(6.022X10^23) X 0.25} molecules
= 1.5055X10^23 molecules
So, there are 1.5055X10^23 molecules present in 0.25 moles of Hydrogen gas.