Question

Among K, Ca, Fe and Zn, the element which can form more than one binary compound with chlorine are:
A. Zn
B. K
C. Ca
D. Fe

Answer 1

Hint: To begin with, we must understand the concept of oxidation state, which is defined as the number of electrons an atom gains or losses when interacting with another species from its outermost shell.

Complete Step by Step Solution:
There are two different sorts of oxidation numbers:
Positive oxidation numbers, which the atom displays when it loses electrons from the outermost shell, and negative oxidation numbers, which the atom displays when it accepts electrons on the outermost shell from the environment.

Fe has two oxidation states, $ + 2$ and $ + 3$, which allows it to combine with chlorine to generate more than one binary compound. Since Fe has an atomic number of $26$ and an electronic configuration of $[Ar]3{d^6}4{s^2}$, it will exhibit both $ + 2$ and $ + 3$ oxidation states to achieve stability.

Iron will display a $ + 2$ oxidation state when two of the iron atom's four electrons are lost.
Because the d-orbital exhibits remarkable stability when half occupied, iron will occasionally remove one electron from the 3d orbital in addition to the two electrons from the 4s orbital to increase stability. As a result, iron will exhibit a $ + 3$ oxidation state.

However, Ca only exhibits a $ + 2$ oxidation state, K only exhibits a $ + 1$ oxidation state, and Zn only exhibits a $ + 2$ oxidation state.
Only the $ - 1$ oxidation state of chlorine is present.
Hence option D is correct.

Note: Some of you might be thinking that iron might exhibit $ - 4$ oxidation in order to complete the d-orbital and achieve the best stability, but this assumption is false because adding four electrons requires more energy than taking away two or three.