Question

The number of protons, neutrons and electrons in ${}_{89}^{231}Y$ are:

• A. 89, 89, 242
• B. 89. 142, 89
• C. 89, 71, 89
• D. 89, 231, 89

Answer 1

The correct option is B

89. 142, 89

Atomic number of the element Y = 89
Mass number of the element Y = 231
$Atomicnumber=numberofprotons=numberofelectrons$
Number of protons = number of electrons = 89
Number of neutrons = Mass number – Atomic number
Number of neutrons = 231 – 89 = 142