How many molecules are there in 15 g of hydrogen?

The mass of hydrogen is 15 g.
Let’s determine the number of hydrogen molecules.
In order to determine the number of hydrogen molecules, you must use the following formula.
N = n * Na.
Where N is the number of molecules of the substance.
n is the amount of substance.
Na is Avogardo’s number, a constant 6.02 * 10 ^ 23.
First, you need to determine the amount of hydrogen substance. To do this, use the following formula.
n = m / M.
M (H2) = 1 * 2 = 2 g / mol.
n = 15 g / 2 g / mol = 7.5 mol.
N = 7.5 * 6.02 * 10 ^ 23 = 45.15 * 10 ^ 23 molecules.
Answer: the number of hydrogen molecules is 45.15 * 10 ^ 23 molecules.