Question

Which of the following pairs represent an
isobar?
(1) 12 P + 13 N and 15 P + 13 N
(2) 12 P +14 N and 13 P and 13 N
(3) 13 P +13 N and 10 P + 13 N
(4) 13 P + 14 N and 12 P and 14 N​

Answer 1

number 3 gives what I hadda ask !