Question

calculate no of molecules of 18g of H2​

Answer 1

Hydrogen has a molecular mass of about 2 g/mole, so 18 g of hydrogen is 9 moles. One mole is 6.022 X 10^23 molecules, so the number of molecules in 18 g of hydrogen is 9X this, or approximately 54 X 10^23 = 5.4 X 10^24 molecules. Hydrogen has a molecular mass of about 2 g/mole, so 18 g of hydrogen is 9 moles.

Answer 2

No. of moles = mass/molecular mass = 18/2 = 9

No. of molecules = 9 x 6.023 x 10-²³