If an animal has 42 chromosomes in its normal, non-gamete or somatic cells, what term would be given to the gametes that have 21 chromosomes

The answer is haploid because they have half as many chromosomes(21) as diploid cells which are somatic or body cells. Haploid cells are things like sperm which combine with the female reproductive cell to make a 42 chromosome human cell.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.