21.

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]⁺

In a mixture, two enantiomers are found to be present in 85% and 15% respectively. The enantiomeric excess (ee) is

• 85%

• 15%

• 70%

• 60%

In the Lassaigne's test for the detection of nitrogen in an organic compound, the appearance of blue coloured compound is due to

• ferric ferricyanide

• ferrous ferricyanide

• ferric ferrocyanide

• ferrous ferrocyanide

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

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

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

• Au(CN)${}_3^{-}$ and Zn(CN)${}_6^{2-}$

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

The atomic number of cerium (Ce) is 58. The correct electronic configuration of Ce³⁺ ion is

• [Xe]4f¹

• [Kr]4f¹

• [Xe]4f¹³

• [Kr]4d¹

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

• PCl₅, SO₂

• OPCl₃, SOCl₂

• PCl₅, SO₂, S₂Cl₂

• OPCl₃, SO₂, S₂Cl₂

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

• O${}_2^{-}$

Cold ferrous sulphate solution on absorption of NO develops brown colour due to the formation of

• paramagnetic [Fe(H₂O)₅(NO)]SO₄

• dimagnetic [Fe(H₂O)₅(NO)]SO₄

• paramagnetic [Fe(H₂O)₅(NO₃)][SO₄]₂

• diamagnetic [Fe(H₂O)₄(SO₄)]NO₃

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

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

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

• $\frac{\mathrm{m}}{{\mathrm{a}}^3}$

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