The spin-only magnetic moment of ${\mathrm{Ce}}^{3+}$ is:
1. 3.25
2. 1.73
3. zero
4. 4.21

Match the List I with List II:

1. ${\mathrm{Ti}}^{3+},{\mathrm{V}}^{3+},$ ${\mathrm{Cu}}^{+}$

2. ${\mathrm{Sc}}^{3+},$ ${\mathrm{Mn}}^{2+},$ ${\mathrm{Fe}}^{3+}$

3. ${\mathrm{Ti}}^{3+},{\mathrm{V}}^{3+},$ ${\mathrm{Mn}}^{2+},$ ${\mathrm{Fe}}^{3+},$ $$ ${\mathrm{Co}}^{2+}$

4. None of the above.

$\mathrm{a}. {\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+{\mathrm{H}}^{+}+{\mathrm{Fe}}^{2+}\to 2{\mathrm{Cr}}^{3+}+{\mathrm{Fe}}^{3+}+{\mathrm{H}}_2\mathrm{O}$
$\mathrm{b}. {\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+{\mathrm{H}}^{+}+ {\mathrm{I}}^{-}\to {\mathrm{Cr}}^{3+}+{\mathrm{H}}_2\mathrm{O}+{\mathrm{I}}_2$
$\mathrm{c}. {\mathrm{H}}_2\mathrm{S}+{\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+{\mathrm{H}}^{+}\to {\mathrm{Cr}}^{3+}+{\mathrm{H}}_2\mathrm{O}+\mathrm{S}$

The correct reactions are-

1. a,c

2. b, c

3. a, b

4. a, b, c

The correct statement(s) about transition elements are:  

The correct statement regarding inner transition elements is:

$\left(\mathrm{i}\right) {\mathrm{FeCr}}_2{\mathrm{O}}_4 \hspace{0.17em}+ \mathrm{NaOH} + {\mathrm{O}}_2 \underset{}{\to } ... \mathrm{X}.....+ {\mathrm{Fe}}_2{\mathrm{O}}_3 +\hspace{0.17em}{\mathrm{H}}_2\mathrm{O}$
$\left(\mathrm{ii}\right) {\mathrm{K}}_2{\mathrm{MnO}}_4 +\hspace{0.17em}{\mathrm{O}}_3 + {\mathrm{H}}_2\mathrm{O} \stackrel{}{\to } .....\mathrm{Y}.... + \mathrm{KOH} + {\mathrm{O}}_2$

The products X and Y in the above reactions (i) and (ii) are respectively:

$1. {\mathrm{Na}}_2{\mathrm{Cr}}_2{\mathrm{O}}_{7 }, {\mathrm{K}}_2{\mathrm{MnO}}_8$
$2. {\mathrm{Na}}_2{\mathrm{CrO}}_4, {\mathrm{KMnO}}_4$
$3. {\mathrm{Na}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7, {\mathrm{KMnO}}_4$
$4. {\mathrm{NaCrO}}_4, {\mathrm{MnO}}_2$

The correct statement(s) about transition elements is/are:  

The $\mathrm{E}°({\mathrm{M}}^{2+}/\mathrm{M})$ value for copper is positive (+0.34 V), because