Chloride of which of the following element is coloured

Predict which of the following will be coloured in aqueous solution? $Ti ^{3+}, V ^{3+}, Cu ^{+},$ $Sc ^{3+}, Mn ^{2+}, Fe ^{3+}$ and $Co ^{2+} .$ Give reasons for each. 

Which of the following ion is diamagnetic 

The spin-only magnetic moment value of $M ^{3+}$ ion (in gaseous state) from the pairs $Cr ^{3+} / Cr ^{2+}$, $Mn ^{3+} / Mn ^{2}, Fe ^{3+} / Fe ^{2+}$ and $Co ^{3+} / Co ^{2+}$ that has negative standard electrode potential, is $B.M...........$ [Nearest integer]

For $M ^{2+} / M$ and $M ^{3+} / M ^{2+}$ systems, the ${E^\Theta }$ values for some metals are as follows:

$Cr ^{2+} / Cr \,-0.9 \,V$

$Cr ^{3} / Cr ^{2+}\,-0.4 \,V$

$Mn ^{2+} / Mn \,-1.2\, V$

$Mn ^{3+} / Mn ^{2+}\,+1.5 \,V$

$Fe ^{2+} / Fe\, -0.4 \,V$

$Fe ^{3+} / Fe ^{2+}\,+0.8\, V$

Use this data to comment upon:

$(i)$ The stability of $Fe ^{3+}$ in acid solution as compared to that of $Cr ^{3+}$ or $Mn ^{3+}$ and

$(ii)$ The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.

Ammonia is a Lewis base. It forms complexes with cations. Which one of the following cations does not form complex with ammonia