Question

What happen to a nucleus that undergoes alpha decay?

A. the number of protons and neutrons increase by 2 each

B. the number of protons and neutrons decrease by 2 each

C. the number of protons and neutrons increase by 1 each

D. the number of protons and neutrons decrease by 1 each

Answer 1

Alpha decay means lose of alpha partical.

Alpha partical is Helium nucleus( 2He4)

He has 2 units of atomic number ( number of electrons) & 4 units of atomic mass number ( number of protons)

So number of neutrons = atomic mass number -atomic number

                                      = 4-2

                                     = 2

So upon decay of alpha partical the parent nucleus , the number of protons decreased by 2 units

                                                                                    the number of neutrons decreased by 2 units

Therefore option (B) is correct.