Answer
a. Z = 15, n =18
b. Z = 19, n = 21
c. Z = 86, n = 136
d. Z = 43, n = 56
Work Step by Step
1. Knowing that this form represents "A" and "Z" in these positions: $^A_ZX$.
a. Z = 15
b. Z = 19
c. Z = 86
d. Z = 43
2. Number of neutrons (n) = A - Z
a. n = 33 - 15 = 18
b. n = 40 - 19 = 21
c. n = 222 - 86 = 136
d. n = 99 - 43 = 56
