Answer :
Neutrons=mass number-atomic number
most S-36 and P-35(both have 20 neutrons) (36-16=20)(35-15=20)
P-33 (33-15=18neutrons)
P-32 (32-15=17 neutrons)
least S-32 and P-31 (both have 16 neutrons) (32-16=16)(31-15=16)
most S-36 and P-35(both have 20 neutrons) (36-16=20)(35-15=20)
P-33 (33-15=18neutrons)
P-32 (32-15=17 neutrons)
least S-32 and P-31 (both have 16 neutrons) (32-16=16)(31-15=16)