Question

Number of protons, neutrons & electrons in the element ${}_{89}^{231}Y$ is:

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

Answer 1

The correct option is C $89,142,89$

The atomic number, Z is 89.
The mass number, A is 231.
The number of protons is equal to the atomic number. It is 89.
The number of electrons is equal to the atomic number. It is 89.
The number of neutrons is the difference in the mass number and atomic number. It is $A-Z=231-89=142$.

Hence, the correct option is $C$