Question

The ion of an element has $3$ positive charges. The mass number of the atom is $27$ and the number of neutrons is $14$. What is the number of electrons in the ion?

• A. $13$
• B. $10$
• C. $14$
• D. $16$

Answer 1

The correct option is B

$10$

The explanation for correct option

(B)$10$

Step1. The calculation for number of electrons in a neutral atom

$$\begin{gathered} \text{Mass number=Number of proton+Number of neutron} \\ 27=\mathrm{Number}\mathrm{of}\mathrm{proton}+14 \\ 13=\mathrm{Number}\mathrm{of}\mathrm{proton} \end{gathered}$$

• As the number of protons is equal to the number of electron in the neutral atom.
• So, the number of electrons in a neutral atom is $13$.

Step2. Calculation of the number of electrons in the ion

• The ion of an element has $3$ positive charges.
• So, the number of electrons in the ion is$13-3=10$.

So, the number of electrons in the ion is $10$.

The explanation for the incorrect options

The number of electrons in the ion is $10$. Hence, the options (A), (C), and (D) are incorrect.

Hence, option (B) is correct. The number of electrons in the ion is $10$.