The catalytic activity of transition elements is related to their

Identify incorrect statement

The element exhibiting most stable $ + \,2$ oxidation state among the following is

$(a)$ Answer the following questions :

$(i)$ Which element of the first transition series has highest second ionisation enthalpy ?

$(ii)$ Which element of the first transition series has highest third ionisation enthalpy ?

$(iii)$ Which element of the first transition series has lowest enthalpy of atomisation ?

$(b)$ Identify the metal and justify your answer.

$(i)$ Carbonyl $M(CO)_5$  $(ii)$  $MO_3F$

Given below are two statements, one is labelled as Assertion $A$ and the other is labelled as Reason $R$.

Assertion $A:$ The spin only magnetic moment value for $\left[ Fe ( CN )_6\right]^{3-}$ is $1.74 BM$, whereas for $\left[ Fe \left( H _2 O \right)_6\right]^{3+}$ is $5.92\,BM$.

Reason $R :$ In both complexes, $Fe$ is present in +3 oxidation state.

In the light of the above statements, choose the correct answer from the options given below:

The transition metal ions responsible for colour in ruby and emerald are, respectively