Answers and explanations:
1) Lead, it is heavier than iron.
2) Lead, since it's heavier, it would have more mass and therefore more atoms.
3) (for sodium) 82.03379 gram x 6.23= 511.070512 grams= 417.05 pounds
(for sucrose) 342.29648(one molar) x .65= 0.4 pound
The sodium would be heavier (not sure if accurate)
4) Because atoms are way too small to count, therefore we use molar masses.