In which of the following oxoanions the oxidation state of the central atom is not the same as that of its group number in the periodic table?

(A) ${{\mathrm{MnO}}_4^{}}^{-}$                               

(B) ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$

(C) ${\mathrm{VO}}_4^{3-}$                                 

(D) ${\mathrm{FeO}}_4^{2-}$

At $300°\mathrm{C},<mspace\; width="1em"></mspace>{\mathrm{FeCl}}_3<mspace\; width="1em"></mspace>:$

1. Decomposes into ${\mathrm{FeCl}}_2<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{Cl}}_2.$               

2. Decomposes into $\mathrm{Fe}<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{Cl}}_2.$

3. Sublimes go give liquid ${\mathrm{FeCl}}_3$                         

4. Sublimes to give gaseous dimmer ${\left({\mathrm{FeCl}}_3\right)}_2.$

Anhydrous ferric chloride is prepared by

(1) Heating hydrated ferric chloride at a high temperature in a stream of air.

(2) Heating metallic iron in a stream of dry chlorine gas.

(3) Reaction of ferric oxide with HCl (aq).

(4) Reaction of metallic iron with HCl (aq).

Anhydrous ferrous sulphate on heating gives :

1. Both ${\mathrm{SO}}_2<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{SO}}_3$                         

2. ${\mathrm{SO}}_2<mspace\; width="1em"></mspace>\mathrm{only}$

3. ${\mathrm{SO}}_3<mspace\; width="1em"></mspace>\mathrm{only}$                                       

4. ${\mathrm{Fe}}_2{\left({\mathrm{SO}}_4\right)}_3<mspace\; width="1em"></mspace>\mathrm{only}$

${\mathrm{FeCl}}_3.6{\mathrm{H}}_2\mathrm{O}+\mathrm{C}<mspace\; width="1em"></mspace>{\left({\mathrm{CH}}_3\right)}_2{\left({\mathrm{CH}}_3\mathrm{O}\right)}_2\to \mathrm{Products}$

Reaction products are :

(A) ${\mathrm{FeCl}}_3,<mspace\; width="1em"></mspace>{\mathrm{CH}}_3\mathrm{OH}<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{CH}}_3{\mathrm{COCH}}_3$                       

(B) $\left({\mathrm{CH}}_3\mathrm{O}\right)\mathrm{Fe},<mspace\; width="1em"></mspace>\mathrm{HCl}<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{O}$

(C) ${\mathrm{FeCl}}_2,<mspace\; width="1em"></mspace>\mathrm{HCl}<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{CH}}_3{\mathrm{COCH}}_3$                             

(D) $\mathrm{Fe}{\left(\mathrm{OH}\right)}_3,<mspace\; width="1em"></mspace>{\mathrm{FeCl}}_3<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{CH}}_3{\mathrm{COCH}}_3$

Excess of Kl reactions with ${\mathrm{CuSO}}_4$ solution and ${\mathrm{Na}}_2{\mathrm{SO}}_4$ solution is added to it. Which of the following statement is incorrect for this reaction ?

(1) Evolved ${\mathrm{I}}_2$ is reduced                                     

(2) ${\mathrm{Cul}}_2$ is formed

(3) ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$ is oxides                                         

(4) ${\mathrm{Cu}}_2{\mathrm{l}}_2$ is formed.

Select the correct statement :

(1) ${\mathrm{PH}}_3$ reduces ${\mathrm{AgNO}}_3$ to metallic Ag.

(2) Organic tissues turn ${\mathrm{AgNO}}_3$ black by reducing it to Ag.

(3) $\mathrm{AgCN}<mspace\; width="1em"></mspace>$is soluble in $\mathrm{KCN}$.

(4) All are correct statements.

The yellow colour solution of ${\mathrm{Na}}_2{\mathrm{CrO}}_4$ changes to orange-red on passing ${\mathrm{CO}}_2$ gas due to the formation of :

(1) ${\mathrm{CrO}}_5$                                         

(2) ${\mathrm{CrO}}_3$

(3) ${\mathrm{Na}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$                                 

(4) ${\mathrm{Cr}}_2{\mathrm{O}}_3$

${\mathrm{FeCr}}_2{\mathrm{O}}_4+4{\mathrm{Na}}_2{\mathrm{CO}}_3+{\mathrm{O}}_2\stackrel{\mathbf{Fusion}}{\to }\left[\mathbf{X}\right]\underset{<mspace\; width="1em"></mspace>\mathbf{\hspace{0.17em}}\mathbf{\hspace{0.17em}}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\hspace{0.17em}}<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>}{\overset{{\mathbf{H}}^{\mathbf{+}}}{\to }}\left[\mathbf{Y}\right]\underset{{\mathbf{H}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{2}}}{\overset{{\mathbf{H}}^{\mathbf{+}}}{\to }}\left[\mathbf{Z}\right]$

Which of the following statements is true for the compounds [X], [Y] and [Z] ?

${\mathrm{KMnO}}_4$ on treatment with conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$ forms a compound (X) which decomposes explosively on heating forming (Y). The (X) and (Y) are respectively :

(A) ${\mathrm{Mn}}_2{\mathrm{O}}_7,<mspace\; width="1em"></mspace>{\mathrm{MnO}}_2$                                       

(B) ${\mathrm{Mn}}_2{\mathrm{O}}_7,<mspace\; width="1em"></mspace>{\mathrm{Mn}}_2{\mathrm{O}}_3$

(C) ${\mathrm{MnSO}}_4,<mspace\; width="1em"></mspace>{\mathrm{MnO}}_2$                                       

(D) ${\mathrm{Mn}}_2{{\mathrm{O}}_3}^{-},<mspace\; width="1em"></mspace>{{\mathrm{MnO}}_4}^{2-}$