Suppose for element X with following representation

_zX^A

Where A = Mass Number of Element and Z = Atomic Number of the element.

(i) ₆C¹³

Mass Number of Carbon, A = 13

Atomic Number of Carbon, Z = 6

Number of protons = Number of Electrons = Atomic Number =6

Number of neutrons = A – Z

= 13-6 = 7

(ii) ₈O¹⁶

Mass Number of Oxygen, A = 16

Atomic Number of Oxygen, Z = 8

Number of protons = Number of Electrons = Atomic Number =6

Number of neutrons = A – Z

= 16-8= 8

(iii) ₁₂Mg²⁴

Mass Number of Magnesium, A = 24

Atomic Number of Magnesium, Z = 12

Number of protons = Number of Electrons = Atomic Number =6

Number of neutrons = A – Z

= 24-12 = 12

(iv) ₂₆Fe⁵⁶

Mass Number of Iron, A = 56

Atomic Number of Iron, Z = 26

Number of protons = Number of Electrons = Atomic Number =6

Number of neutrons = A – Z

= 56-26 = 30

(v) ₃₈Sr⁸⁸

Mass Number of Strontium, A = 56

Atomic Number of Strontium, Z = 26

Number of protons = Number of Electrons = Atomic Number =6

Number of neutrons = A – Z

= 88-38= 50