which pair of atoms represent nuclei that have the same number of neutrons?

Question

a Co36 and Co 58
b. Mn57 and Fe 57
c. Ni 58 and Fe 57
d. Ni 58 and Co 57
e. Ni 59 and Fe 56

Answer 1

#protons + #neutrons = mass number.
Example:
Fe56 is
protons = 26
mass number = 56
26 + ? = 56
? = number neutrons = 56-26 = 30