The magnetic moment (in $\mu_{B}$ ) of
[Ni(dimethylglyxoimate) ${ }_{2}$ ] complex is closest to $......$

Which of the following is wrongly matched

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.

A copper salt is isomorphic with $ZnS{O_4}$, the salt will be

Which of the following statements are correct?

$(A)$ The $M ^{3+} / M ^{2+}$ reduction potential for iron is greater than manganese

$(B)$ The higher oxidation states of first row $d$ block elements get stabilized by oxide ion.

$(C)$ Aqueous solution of $Cr ^{2+}$ can liberate hydrogen from dilute acid.

$(D)$ Magnetic moment of $V ^{2+}$ is observed between $4.4-5.2\,BM$

Choose the correct answer from the options given below:

In which of the following pairs are both the ions coloured in aqueous solution ?

(At. no. : $Sc = 21, Ti = 22, Ni = 28,$$ Cu = 29, Co = 27$)