Identify the pair of elements in which number of electrons in $(n-1)$ shell is same

Question

Aicharya · Accepted Answer

1. Fe electronic configuration $=\left[\mathrm{Fe} \Rightarrow 1 \mathrm{~s}^2 2 \mathrm{~s}^2 2 \mathrm{p}^6 3 \mathrm{~s}^2\right.$ $\left.3 \mathrm{p}^6 4 \mathrm{~s}^2 3 \mathrm{~d}^6\right]$ Here $(n-1)$ shell is $3 d$ which have 6 electron. 2. mn electronic configuration $\left[\mathrm{Mn} \Rightarrow 1 \mathrm{~s}^2 2 \mathrm{~s}^2 2 \mathrm{p}^6 3 \mathrm{~s}^2\right.$ $\left.3 \mathrm{p}^6 4 \mathrm{~s}^2 3 \mathrm{~d}^5\right]$ ( $\mathrm{n}-1$ ) shell have 5 electrons 3. Zn electronic configuration $\left[\mathrm{Zn} \Rightarrow 1 \mathrm{~s}^2 2 \mathrm{~s}^2 2 \mathrm{p}^6 3 \mathrm{~s}^2\right.$ $3 \mathrm{p}^6 4 \mathrm{~s}^2 3 \mathrm{~d}^{10}$ ] [ $\mathrm{n}-1$ ) shell have 10 electron] 4. Sc electronic configuration $\left[\mathrm{Sc} \Rightarrow 1 \mathrm{~s}^2 2 \mathrm{~s}^2 2 \mathrm{p}^6 3 \mathrm{~s}^2 3 \mathrm{p}^6\right.$ $4 \mathrm{~s}^2 3 \mathrm{~d}^1$ ] $(n-1)$ shell have 1 electron. Kelectronic configuration is $\left[\mathrm{K} \Rightarrow 1 \mathrm{~s}^2 2 \mathrm{~s}^2 2 \mathrm{p}^6 3 \mathrm{~s}^2 3 \mathrm{p}^6 4 \mathrm{~s}^1\right]$ $(n-1)$ shell have 6 electron. Cr electronic configuration is $\left[\mathrm{Cr} \Rightarrow 1 \mathrm{~s}^2 2 \mathrm{~s}^2 2 \mathrm{p}^6 3 \mathrm{~s}^2\right.$ $\left.3 p^6 4 s^1 3 d^5\right]$ Here $(n-1)$ shell have 5 electron.
So $\mathrm{Mn}, \mathrm{Cr}$ have same number of electron in $(\mathrm{n}-1)$ shell.

Identify the pair of elements in which number of electrons in $(n-1)$ shell is same

Solution