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_(3)F`

Explanation

(i) Cu. This is because electronic configuration of Cuis `3d^(10)4s^(1)`. After loss of 1st electron, it acquires stable configuration of `3d^(10) `. Hence, removal removal of 2nd electron is very difficult.
(ii) Zn. This is because `Zn= 3d^(10) 4s^(2)` and `Zn^(2+) = 3d^(10)` which is again fully filled and hence is very stable. Removal of 3rd electron requires very high energy.
(iii) Zn. This is because it has completely filled 3d subshell and no unpaired electron is availableformetallic bonding .
(b) (i) Following EAN rule
(ii) `overset(x-2)(MO_(3))F^(-1), x-6-1=0, x= +7, i.e., ` M is in oxidation state `+7` Mn shows an oxidation state of `+7`. Hence, the compound is `MnO_(3)F`