Question

The number of d-electrons in ${Fe^{2+} (Z=26)}$ is not equal to the number of electrons in which one of the following?

• A. d-electrons in Fe (Z=26)
• B. p-electrons in Ne (Z=10)
• C. s-electrons in Mg (Z=12)
• D. p-electrons in Cl (Z=17)

Answer 1

The Correct Option is D

To solve this question, we need to compare the number of d-electrons in ${Fe^{2+} (Z=26)}$ with the number of specific type electrons in other elements mentioned in the options.

Let's analyze each option one by one:

1. d-electrons in ${Fe (Z=26)}:
   The electronic configuration of neutral Iron (Fe) is ${[Ar] 3d^6 4s^2}. Therefore, the number of d-electrons in Fe is 6.
2. p-electrons in ${Ne (Z=10)}:
   The electronic configuration of Neon (Ne) is ${1s^2 2s^2 2p^6}. Thus, the number of p-electrons is 6.
3. s-electrons in ${Mg (Z=12)}:
   The electronic configuration of Magnesium (Mg) is ${1s^2 2s^2 2p^6 3s^2}. Therefore, the number of s-electrons is 4 (2 from 1s and 2 from 3s).
4. p-electrons in ${Cl (Z=17)}:
   The electronic configuration of Chlorine (Cl) is ${1s^2 2s^2 2p^6 3s^2 3p^5}. Hence, the number of p-electrons is 11 (6 from 2p and 5 from 3p).

Now, let's find the electronic configuration of ${Fe^{2+}}:

The neutral Fe atom loses two electrons to form ${Fe^{2+}}. The removal of electrons occurs from the 4s orbital first, followed by the 3d orbitals due to energy considerations. Thus, the electronic configuration of ${Fe^{2+}} is ${[Ar] 3d^6}. Therefore, the number of d-electrons in ${Fe^{2+}} is 6.

Comparing all the options:

• d-electrons in ${Fe^{2+}}$: 6
• d-electrons in Fe: 6
• p-electrons in Ne: 6
• s-electrons in Mg: 4
• p-electrons in Cl: 11

Clearly, the number of d-electrons in ${Fe^{2+}} (6) is not equal to the number of p-electrons in Cl (11).

Conclusion: The number of d-electrons in ${Fe^{2+}} is not equal to the number of p-electrons in ${Cl (Z=17)}.