The number of hydrogen atoms present in $25.6 \mathrm{g}$ of sucrose $\left({\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}\right)$which has a molar mass of $342.3 \mathrm{g}$is 

No. of moles of sucrose $=\frac{25.6}{342.3}=0.075$

1 mole of sucrose contains $22\times 6.023\times {10}^{23} \mathrm{of} \mathrm{H}-\mathrm{atom}$

$0.075$ moles of sucrose contain

$=9.91\times {10}^{23} \mathrm{of} \mathrm{H}-\mathrm{atoms}.$