The correct statement(s) about interstitial compounds is/are:

1.	Transition elements are large in size and contain multiple interstitial sites.
2.	Transition elements can trap atoms of other elements.
3.	Interstitial compounds are chemically inert.
4.	All of the above.

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.

$\mathrm{a}.<mspace\; width="1em"></mspace>{\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+{\mathrm{H}}^{+}+{\mathrm{Fe}}^{2+}\to 2{\mathrm{Cr}}^{3+}+{\mathrm{Fe}}^{3+}+{\mathrm{H}}_2\mathrm{O}$
$\mathrm{b}.<mspace\; width="1em"></mspace>{\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+{\mathrm{H}}^{+}+<mspace\; width="1em"></mspace>{\mathrm{I}}^{-}\to {\mathrm{Cr}}^{3+}+{\mathrm{H}}_2\mathrm{O}+{\mathrm{I}}_2$
$\mathrm{c}.<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{S}+{\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+{\mathrm{H}}^{+}\to {\mathrm{Cr}}^{3+}+{\mathrm{H}}_2\mathrm{O}+\mathrm{S}$

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:

$\left(\mathrm{i}\right)<mspace\; width="1em"></mspace>{\mathrm{FeCr}}_2{\mathrm{O}}_4<mspace\; width="1em"></mspace>\hspace{0.17em}+<mspace\; width="1em"></mspace>\mathrm{NaOH}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{O}}_2<mspace\; width="1em"></mspace>\underset{}{\to }<mspace\; width="1em"></mspace>...<mspace\; width="1em"></mspace>\mathrm{X}.....+<mspace\; width="1em"></mspace>{\mathrm{Fe}}_2{\mathrm{O}}_3<mspace\; width="1em"></mspace>+\hspace{0.17em}{\mathrm{H}}_2\mathrm{O}$
$\left(\mathrm{ii}\right)<mspace\; width="1em"></mspace>{\mathrm{K}}_2{\mathrm{MnO}}_4<mspace\; width="1em"></mspace>+\hspace{0.17em}{\mathrm{O}}_3<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{O}<mspace\; width="1em"></mspace>\stackrel{}{\to }<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>.....\mathrm{Y}....<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>\mathrm{KOH}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{O}}_2$

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

$1.<mspace\; width="1em"></mspace>{\mathrm{Na}}_2{\mathrm{Cr}}_2{\mathrm{O}}_{7<mspace\; width="1em"></mspace>},<mspace\; width="1em"></mspace>{\mathrm{K}}_2{\mathrm{MnO}}_8$
$2.<mspace\; width="1em"></mspace>{\mathrm{Na}}_2{\mathrm{CrO}}_4,<mspace\; width="1em"></mspace>{\mathrm{KMnO}}_4$
$3.<mspace\; width="1em"></mspace>{\mathrm{Na}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7,<mspace\; width="1em"></mspace>{\mathrm{KMnO}}_4$
$4.<mspace\; width="1em"></mspace>{\mathrm{NaCrO}}_4,<mspace\; width="1em"></mspace>{\mathrm{MnO}}_2$

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