Which of the following is a fusion reaction?
a.) uranium-235 absorbing a neutron and splitting into xenon-140, strontium-94, and two neutrons
b.) hydrochloric acid combining with sodium hydroxide to form nacl and water
c.) carbon-14 decaying into nitrogen-14 and a beta particle
d.) curium-246 combining with carbon-12 to form nobelium-254 and four neutrons

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.  

you need to have a picture of the atom that way we can answer it