21.

Addition of sodium thiosulphate solution to a solution of silver nitrate gives X as white precipitate, insoluble in water but soluble in excess thiosulphate solution to give Y. On boiling in water, Y gives Z. X, Y and Z respectively are

• Ag₂S₂O₃, Na₃[Ag(S₂O₃)₂], Ag₂S

• Ag₂SO₄, Na[Ag(S₂O₃)₂], Ag₂S₂

• Ag₂S₂O₃, Na₅[Ag(S₂O₃)₃], AgS

• Ag₂SO₃, Na₃[Ag(S₂O₃)₂], Ag₂O

The total number of aromatic species generated in the following reactions is

• zero

• 2

• 3

• 4

Optical isomerism is exhibited by (ox= oxalate anion; en= ethylenediamine).

• cis-[CrCl₂(ox)₂]^3-

• [Co(en)₃]³⁺

• trans-[CrCl₂(ox)₂]^3-

• [Co(ox) (en)₂]⁺

Extraction of gold (Au) involves the formation of complex ions X and Y.

Gold ore $\underset{{\mathrm{CN}}^{-}, {\mathrm{H}}_2\mathrm{O}, {\mathrm{O}}_2}{\overset{\mathrm{Roasting}}{\to }}$ HO^- + X $\stackrel{\mathrm{Zn}}{\to }$ Y + Au

X and Y respectively are

• AuCN${}_2^{-}$ and Zn(CN)${}_4^{2-}$

• Au(CN)${}_4^{3-}$ and  Zn(CN)${}_{\mathrm{}}^{$ {}_4^{2-}$}$

• Au(CN)${}_3^{-}$ and Zn(CN)${}_6^{4-}$

• Au(CN)${}_4^{-}$ and Zn(CN)${}_3^{-}$

Sulphuryl chloride (SO₂Cl₂) reacts with white phosphorus (P₄) to give

• PCl₅, SO₂

• OPCl₃, SOCl₂

• PCl₅, SO₂, S₂Cl₂

• OPCl₃, SO₂, S₂Cl₂

In the following compound, the number of sp-hybridised carbons are

CH₂ = C = CH - CN(CH) - C ≡ CH

• 2

• 3

• 4

• 5

For the reaction A + 2B → C, the reaction rate is doubled, if the concentration of A is doubled. The rate is increased by four times when concentrations of both A and B are increased by four times. The order of the reaction is

• 3

• 0

• 1

• 2

In aqueous alkaline solution, two electrons reduction of HO${}_2^{-}$ gives

• HO^-

• H₂O

• O₂

• ${\mathrm{O}}_2^{-}$

Suppose the mass of a single Ag-atom is m. Ag metal crystallises in fcc lattice with unit cell of length a. The density of Ag metal in terms of a and 'm' is

• $\frac{4\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{2\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{\mathrm{m}}{4{\mathrm{a}}^3}$

At a particular temperature, the ratio of equivalent conductance to specific conductance of a 0.01 N NaCl solution is

• 10⁵ cm³

• 10³ cm³

• 10 cm³

• 10⁵ cm²