1 gram of hydrogen contains $6\times {10}^{23} \mathrm{atoms}.$ Then 4 grams of He contains

For noble gases, atomic mass is equal to molecular mass. Because they are mono atomic in the state.

4 gram of He = 1 mol He atoms = $6.023\times {10}^{23} \mathrm{atoms}=6\times {10}^{23} \mathrm{atoms}$