Given:

Mass Number = 56

Percentage of neutron = 30.4% more as compared electrons

Let Number of electrons = number of protons = p

Let number of protons = p

Let number of neutrons= n

Since the ion has three units of positive charge. So the ion is tripositive.

p + 3 + n = 56

p + 3 + {p + [30.4× p] / 100} = 56

p + 3 + 1.304p = 56

2.304p = 53

p = 53 / 2.304

p = 23

Therefore, the number of protons = 23 + 3

= 26

Atomic Number = 26

The element is chlorine.

The atomic symbol is 56₂₆Cl.