Question

there are ______ neutrons in the stable isotope of rhenium (re - 185).
a 110
b 134
c 125
d 90

Explanation:

Step1: Recall atomic number of rhenium

The atomic number of rhenium (Re) is 75.

Step2: Use neutron - mass number relationship

The number of neutrons $n$ is given by the formula $n = A - Z$, where $A$ is the mass number and $Z$ is the atomic number. For Re - 185, $A = 185$ and $Z=75$. So $n=185 - 75$.

Step3: Calculate the number of neutrons

$n = 110$.

Answer:

A. 110