Question

The number of electrons plus neutrons in ${}_{19}^{40}{K}^{+}$is

• A. 38
• B. 59
• C. 39
• D. 40

Answer 1

Answer: (C)

For, ${}_{19}^{40}{K}^{+}$
Number of electrons in $K^{+}=18$
Number of neutrons in $K^{+}=40-19=21$
$\Rightarrow$ Sum of electron $+$ neutron
$=18+21=39$