Plutonium-196 has an atomic number of 78. It has neutrons.

118 neutrons

Explanation:

There are three subatomic particles in an atom namely: electron, neutron and proton. The mass number of an atom is calculated by adding the proton no. (atomic mass) + neutron no.

That is;

Mass no. = proton no. + neutron no.

This means that to obtain the neutron no. in the atom of an element, we subtract the no of protons or atomic mass from the mass number.

According to this question, Plutonium-196 is said to have an atomic number of 78. The mass no. is 196, hence, the number of neutrons is:

196 - 78

= 118 neutrons.

m=9

step-by-step explanation: