Question 8 of 15 Mitochondrial DNA (mtDNA) is exclusively inherited from the mother.
Because of its unique inheritance pattern, how can it be helpful to genetic
researchers?
A. It provides insight into sex-linked traits that are passed through
the X chromosome.

B. It opens the possibility of asexual reproduction in organisms that
previously reproduced sexually.

C. It allows scientists to trace maternal lineages back many
generations and show evolutionary relationships.

D. It helps scientists better understand genetic conditions such as
male pattern baldness and colorblindness.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.