An atom has 98 protons and 151 neutrons. If it undergoes alpha decay, what are the number of protons and neutrons, respectively, in the daughter nucleus?

Answer 1

The atom goes down two in the atomic number and 4 in the mass number...
If this atom has 98 protons, the element is Californium (Cf).
The atomic number becomes 96.
Then since the mass is 249 amu (98 protons+151 neutrons) usually, it goes down by 4. So now it is 245.

Therefore the number of protons in the new atom is 96 and the number of neutrons is 149 (245-96).