Question

Which of the following metals exhibit more than one oxidation state? \[\]
(A) $Na$
(B) $Mg$
(C) $Fe$
(D) All

Answer 1

Hint: Positive oxidation is seen when an atom loses electrons and negative oxidation state is seen when an atom accepts electrons.

Complete Step by Step Solution:
s and p block elements are called representative elements. S block consists of group $1$ and group $2$ which have \[ + 1\]and \[ + 2\]stable oxidation stateS respectively as they lose electrons to gain noble gas configuration. Whereas p blocks has negative oxidation state as they have a tendency to accept electrons from the metals. But d block shows mid-way properties between s and p block. The d block elements are called transition elements that bridge the two block elements. The d block shows variable oxidation state.

For example, \[M{n^{ + 2}}\]has \[5\] electrons in its d subshell. If one electron is removed from the d subshell, the oxidation state is. Similarly, on removing an electron from d subshell, various oxidation stateS can be formed. Manganese is known to have a maximum number of oxidation stateS. Due to this property of d block elements, they are widely used in redox chemistry and they can decrease or increase their oxidation states easily. D block shows variable oxidation state as the d subshell is not so penetrated thus it is easy to remove an electron. But s and p subshells have more nuclear attraction acting on them.
Hence, the correct option is C as \[Fe\]is a d block element and shows various oxidation stateS like \[ + 2\]and \[ + 3\]. \[Na\]and \[Mg\]are s blocks having only a single oxidation state that is \[ + 1\]and\[ + 2\]respectively.

Note: Magnesium has two electrons in $3s$ subshell. If $1$ electron is lost then it acquires \[ + 1\] oxidation state but it is not considered to be an oxidation state as a single electron is highly unstable.