Answer:
113
Step-by-step explanation:
We are given that the atom of cadmium has 66 neutrons:
Number of neutrons in Cd = 66
Now;
Mass number = ?
The mass number of an element is the sum of the number of protons and number of neutrons
Mass number = number of protons + number of neutrons
By the position of cadmium, it has an atomic number of 47 and this is the number of protons
Mass number = 47 + 66 = 113