Question

The sum of the number of electrons, protons and neutrons in the three isotopes ${(}^{12}C{,}^{13}C{,}^{14}C)$ of carbon is:

• A. 36
• B. 57
• C. 18
• D. 39

Answer 1

The correct option is B 57

Carbon has an atomic number of 6.
Isotopes of carbon are: ${}^{12}C{,}^{13}C{,}^{14}C$

$\begin{array}{cccc}\text{S}ymbol& \text{N}eutrons& \text{P}rotons& \text{E}lectrons\\ {}^{12}C& 6& 6& 6\\ {}^{13}C& 7& 6& 6\\ {}^{14}C& 8& 6& 6\\ & 21& 18& 18\end{array}$
$⟹21+18+18=57$