Question

an atom of hydrogen has a mass of 1.673x10rised to -24 gram how many atoms of hydrogen are there in 20 grams of hydrogen

Answer 1

1.673 x 10^-24 g contain 1 atom of Hydrogen
Then 1 gram would contain 1/1.673 x 10^-24 = 6.0 x 10²³ atoms
Therefore 20 g Hydrogen would contain = 6.0 x 10²³ x 20 = 120 x 10²³ atoms = 1.2 x 10²⁵ atoms.