Question

The number of electrons, neutrons and protons in a species are equal to $10,8$ and $8$ respectively. The proper symbol of the species is :

• A. $\begin{array}{c}16\\ 8\end{array}O$
• B. $\begin{array}{c}18\\ 8\end{array}O$
• C. $\begin{array}{c}18\\ 10\end{array}Ne$
• D. $\begin{array}{c}16\\ 8\end{array}{O}^{2-}$

Answer 1

The correct option is D $\begin{array}{c}16\\ 8\end{array}{O}^{2-}$

The mass number is the sum of the total number of protons and neutrons$=8+8=16$.

The atomic number is the number of protons in the atomic nucleus$=8$.

Element is oxygen and it has an excess of 2 electrons.

So, representation will be ${}_8^{16}{O}^{2-}$.

Hence, option D is correct.