To determine the number of hydrogen atoms in a 5g sample of pure hydrogen, one can use the formula: Number of atoms = Number of moles * Avogadro's Number. The molecular weight of hydrogen is approximately 1g/mol, which means a 5g sample contains 5 moles of hydrogen. Multiplying 5 moles by Avogadro's Number (approximately 6.022 x 10^23) yields the total number of hydrogen atoms. This calculation confirms the importance of Avogadro's Number in quantifying atoms in a given mass of substance. Understanding these concepts is essential for solving related chemistry problems.