Question

for iodine - 131 with a chemical symbol and net charge of i - what is the mass number
25
131
78
53
11
12
56
44
40
100
22
10
13
54

Explanation:

Step1: Recall mass - number concept

The mass number of an isotope is indicated in its name. For iodine - 131, the number 131 represents the mass number. It is the sum of protons and neutrons in the nucleus of the atom.

Answer:

131