Answer:
2.63g
This means that every mole of water molecules will contain 2 moles of hydrogen and 1 mole of oxygen atoms.
To find the percent composition of hydrogen in water, use the molar mass of water and that of hydrogen
2×1.00794g/mol18.0153g/mol×100=11.19%
This means that every 100 g of water will contain a total of 11.19 g of hydrogen. Since your sample has a mass of 23.5 g, it follows that it will contain
23.5g water⋅11.19 g H100g water=2.63 g H