Which of the following imparts green colour to the glass

Which of the following pair both compounds have no exsistance

Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points:

$(i)$ electronic configurations,

$(ii)$ oxidation states,

$(iii)$ ionisation enthalpies, and

$(iv)$ atomic sizes.

Although $\mathrm{Cr}^{3+}$ and $\mathrm{Co}^{2+}$ ions have same number of unpaired electrons but the magnetic moment of $\mathrm{Cr}^{3+}$ is $3.87$ $B.M.$ and that of $\mathrm{Co}^{2+}$ is $4.87$ $B.M.$ Why ?

Which forms coloured salts

Chloro compound of vanadium has only spin magnetic moment of $1.73\, BM$. This vanadium chloride has the formula: