Question: how many atoms in 1 kg of hydrogen?
Answer: The atomic mass of hydrogen is 1 g/mole. To make up 1 kilogram or 1000 g of hydrogen element, 1000 moles of hydrogen is required. Each mole has a Avogadro's number of atoms or 6.023 xx 10^(23) atoms. Thus, 1 kg hydrogen element or 1000 moles of hydrogen have 6.023 xx 10^(26) atoms (or 1000 times the Avogadro's number).