The number of hydrogen bonded water molecule(s) associated with $CuSO_4\cdot 5H_2O$ is

Metals generally melt at very high temperature. Amongst the following, the metal with the highest melting point will be $......$

The ability to form complex compounds by the transitional metal ion is due to

Magnetic moment $2.83\, BM$ is given by which of the following ions ?

(At. nos. $Ti = 22,\,Cr = 24,$ $ Mn = 25,\,Ni = 28$)

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.

Select the diamagnetic coloured compound:-