In dominant-recessive inheritance, the one allele that affects the child's characteristics is called

A dominant allele creates a phenotype individual who have one copy of allele from one parent that can affect the child’s characteristic; the other allele is called recessive, which has no effect on child’s traits. The dominant and recessive inheritance are both beneficial in terms of giving perceptions on the probability of a person inheriting a phenotypes especially with genetic conditions. 

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.