According to the collision theory of chemical reactions:

a. high energy collisions result in few successful reactions as there isn't sufficient time for the products to react.
b. high energy collisions lead to the successful formation of products.
c. low energy collisions result in many successful reactions as there is sufficient time for the reactants to form products.
d. low energy collisions do not occur in the gas phase. all of the above

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.  

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