Answer:
I⁻
Explanation:
The identity of the element is obtained when the proton number is known.
Mass Number = 127
Neutrons = 74
Number of protons is obtained from;
Protons = Mass Number - Number of Neutrons
Protons = 127 - 74 = 53
The element is Iodine and it's symbol is I.
However, The anion derived from the isotope has 54 electrons
A neutral Iodine should have 53 electrons. This means it has gained a single electron. The symbol is now written as;
I⁻