13

‌

6

C : We know that, e = p = Z
where, e = number of electrons, p = number of protons, Z = atomic number
Here, e = 6 and A = 13 [Since A = Mass number]
p = 6
n = A – p = 13 – 6 ⇒ n = 7 [Since A = p + n]
Number of protons = 6 and number of neutrons = 7.

16

‌

8

O : Here, e = 8, p = 8, A = 16
n = A – p = 16 – 8 ⇒ n = 8
Number of neutrons = 8 and number of protons = 8.

24

‌

12

Mg : Here, e = 12, A = 24, p = 12
n = A – p = 24 – 12 ⇒ n = 12
Number of neutrons = 12 and number of protons = 12.

56

‌

26

Fe : Here, e = 26, p = 26, A = 56
n = A – p = 56 – 26 = 30
Number of neutrons = 30 and number of protons = 26.

88

‌

38

Sr : Here, e = 38, A = 88, p = 38
n = A – p = 88 – 38 ⇒ n = 50
Number of neutrons = 50 and number of protons = 38.