Answer
See explanation.
Work Step by Step
a. Hydrogen’s atomic mass is much smaller than lead’s, so 1 kg of H contains more moles than 1 kg of Pb, and many more atoms. Their masses are the same, 1 kg.
b. A mole of each substance contains the same number of atoms. A lead atom has more mass than a hydrogen atom, so the mole of lead has more mass.
