I believe that the correct nuclear equation is the image that I attached.
From the equation we can see that the number of electrons are balanced out, that is:
42 = 43 – 1
42 = 42
Now what’s left to balance is the mass number,
98 + ? = 99
To complete the gap, we need to fill in 1 neutron so that:
98 + 1 = 99
99 = 99
Answer:
a neutron