Which is the correct symbol for an isotope of iodine with 53 protons and 78 neutrons?

131
I Here the answer
53

The answer is 131 I. Hope this helps!

The correct symbol of Iodine with 53 protons and 78 neutrons is shown below.
The symbols comprises two numbers.

Atomic Number:
                         The number highlighted BLUE is the atomic number of Iodine. Atomic number shows the number o protons present in the nucleus.

Mass Number:
                      The number highlighted in RED is the mass number of given Iodine. Mass number is the sum of protons and neutrons present in the nucleus. So,

                     Mass Number  =  # of Protons  +  # of Neutrons

                     Mass Number  =  53  +  78

                     Mass Number  =  131