Question

`S_(1) : Mn^(2+)` compounds more stable than `Fe^(2+)` towards oxidation to their `+3` state.
`S_(2)` : Titanium and copper both in the first series of transition metals exhibits `+1` oxidation state most frequently.
`S_(3) : Cu^(+)` ions is stable in aqueous solutions.
`S_(4)` : The `E^(0)` value for the `Mn^(3+)//Mn^(2+)` couple much more positive than that for `Cr^(3+)//Cr^(2+)` or `Fe^(3+)//Fe^(2+)`,
A. TTFT
B. TFFT
C. TFTT
D. FFTF

Answer 1

Correct Answer - B
`S_(1):` It is because `Mn^(2+)` has `3d^(5)` configuration which has extra stability.
`S_(2):` Not titatnium but copper, because with +1 oxidation state an extra stable configuraiton `3d^(10)` results
`S_(3):`It is not stable as it undergoes disproportionation `2Cu^(+)(aq)toCu^(2+)(aq)+Cu(s).` The `E^(underline(o))` value for this is favourable.
`S_(4)`: Much larger third ionisation energy of Mn (where the required change is `d^(5)` to `d^(4)`) is mainly responsible for this.