Question

The number of electrons with magnetic quantum number $m_{l} = 0$ in chloride ion is

• A. 6
• B. 8
• C. 10
• D. 18

Hint:

In any filled subshell, there are always exactly 2 electrons with $m_{l} = 0$. Count the number of subshells and multiply by 2.

Answer 1

The Correct Option is C

Step 1: Concept
Chloride ion ($Cl^{-}$) has 18 electrons. Configuration: $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6}$.

Step 2: Meaning
Every orbital (defined by specific $n, l, m_{l}$) can hold 2 electrons. Each subshell has exactly one orbital where $m_{l} = 0$.

Step 3: Analysis
$1s$: 2 electrons ($m_{l}=0$); $2s$: 2 electrons ($m_{l}=0$); $2p$: 2 electrons ($m_{l}=0$); $3s$: 2 electrons ($m_{l}=0$); $3p$: 2 electrons ($m_{l}=0$).

Step 4: Conclusion
Total electrons with $m_{l}=0$ is $2 + 2 + 2 + 2 + 2 = 10$. Final Answer: (C)