Question

The number of \( d \) electrons in Fe is equal to which of the following?
(i) Total number of \( s \)-electrons of Mg
(ii) Total number of \( p \)-electrons of Cl 
(iii) Total number of \( p \)-electrons of Ne

• A. i, ii only
• B. ii, iii only
• C. i, iii only
• D. i, ii, iii

Hint:

To compare the number of \( d \)-electrons, look at the electron configuration and count the electrons in the \( d \)-subshell. Similarly, for \( s \)- and \( p \)-electrons, examine their respective subshells.

Answer 1

The Correct Option is C

The element Fe (Iron) has an atomic number of 26. Therefore, its electronic configuration is: \(1s^2\,2s^2\,2p^6\,3s^2\,3p^6\,4s^2\,3d^6\). The number of \(d\) electrons in Fe is 6 from the 3d subshell.

(i) Total number of \(s\)-electrons in Mg:
Mg (Magnesium) has an atomic number of 12, with the electronic configuration: \(1s^2\,2s^2\,2p^6\,3s^2\). The total number of \(s\)-electrons is \(2+2+2=6\).

(ii) Total number of \(p\)-electrons in Cl:
Cl (Chlorine) has an atomic number of 17, with the electronic configuration: \(1s^2\,2s^2\,2p^6\,3s^2\,3p^5\). The total number of \(p\)-electrons is \(6+5=11\).

(iii) Total number of \(p\)-electrons in Ne:
Ne (Neon) has an atomic number of 10, with the electronic configuration: \(1s^2\,2s^2\,2p^6\). The total number of \(p\)-electrons is 6.

Matching the number of \(d\) electrons in Fe (6) with the options:
(i) s-electrons in Mg: 6 - Match
(ii) p-electrons in Cl: 11 - No Match
(iii) p-electrons in Ne: 6 - Match

Thus, the correct answer is: i, iii only.

Answer 2

The electron configuration of iron (Fe) is: \[ {Fe}: [{Ar}] 3d^6 4s^2 \] Thus, the number of \( d \)-electrons in Fe is 6.
Now, let's examine the other options:
- For Magnesium (Mg), the electron configuration is: \[ {Mg}: [{Ne}] 3s^2 \] Thus, the total number of \( s \)-electrons in Mg is 2.
- For Chlorine (Cl), the electron configuration is: \[ {Cl}: [{Ne}] 3s^2 3p^5 \] Thus, the total number of \( p \)-electrons in Cl is 5.
- For Neon (Ne), the electron configuration is: \[ {Ne}: [{He}] 2s^2 2p^6 \] Thus, the total number of \( p \)-electrons in Ne is 6. From the above analysis: 
- The number of \( d \)-electrons in Fe (6) is equal to the total number of \( p \)-electrons in Cl (5) and Ne (6).
Therefore, the correct options are ii and iii only.