How would the composition of an atom change if both the atomic number and mass number each increase by one ?

The atom gains one proton

Explanation:

Basic definitions:

- The atomic number of an atom is the number of protons in the nucleus:

Z = p

where p is the number of protons

- The mass number of an atom is the number of protons + neutrons in the nucleus:

A = p + n

where p is the number of protons and n the number of neutrons

In this problem, both the atomic number and the mass number increases by one unit, so:

Z' = Z + 1

A' = A + 1

Re-writing the two equations in terms of p and n:

p' = p + 1 (1)

p' + n' = (p+n) + 1 (2)

From eq.(1), we see that the number of protons has increased by one unit. Substituting p' from eq.(1) into eq.(2),

(p+1) + n' = (p+n) + 1

p + 1 + n' = p + n +1

--> n' = n

which means that the number of neutrons has not changed.

i think the answer is b