Which stage is the middle stage of speciation? (15 points)

a) the populations become adapted to different environment and eventually become so different that they cannot interbreed to produce fertile offspring.

b)the populations are isolated and thus do not interbreed.

c) the populations become totally seprated from one another.

d) the populations successfully interbreed.

The populations are isolated and thus do not interbreed.

Explanation:

the answer is true.

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.