21.

On heating with concentrated NaOH solution in an inert atmosphere of CO₂ white phosphorus gives a gas. Which of the following statement is incorrect about the gas?

• It is less basic than NH₃

• It is more basic than NH₃

• It is highly poisonous and has smell like rotten fish

• Its solution in water decomposes in the presence of light

Sodium metal crystallises in bee lattice with edge length of 4.29 Å. The radius of sodium atom is

• 2.857 Å

• 1.601 Å

• 2.145 Å

• 1.857 Å

In a first order reaction, the concentration of the reactant is reduced to 12.5% in 1hr. When was it half completed?

• 3hr

• 20min

• 30min

• 15min

The electrolyte having maximum flocculation value for AgI/Ag⁺ sol is

• NaCl

• Na₂S

• Na₂SO₄

• Na₃PO₄

Copper is extracted from copper pyrites by heating in a Bessemer converter. The method is based on the principle that

• copper has more affinity for oxygen than sulphur at high temperature

• iron has less affinity for oxygen than sulphur at high temperature

• copper has less affinity for oxygen than sulphur at high temperature

• sulphur has less affinity for oxygen at high temperature

Which of the following will be able to show geometrical isomerism?

• MA₃B - Square planar

• MA₂B₂ - tetrahedral

• MABCD- saquare planar

• MABCD- tetrahedral

The electronic configuration of Gd²⁺ is (atomic number of Gd is 64).

• [Xe]4f⁸

• [Xe]4f⁷

• [Xe]4f⁷ 5d¹6s²

• [Xe]4f⁷ 5d¹

${\mathrm{MSO}}_4 \stackrel{{\mathrm{NH}}_4\mathrm{OH}}{\to }\underset{\mathrm{White}}{\downarrow \mathrm{X}} \underset{\mathrm{Excess}}{\overset{{\mathrm{NH}}_4\mathrm{OH}}{\to }} \mathrm{Y}\stackrel{{\mathrm{H}}_2\mathrm{S}}{\to } \downarrow \mathrm{Z}$.Here, M and Z are

• Cu, ZnS

• Zn, ZnS

• Fe, FeS

• Al, Al₂S₃

In H₂-O₂ fuel cell the reaction occurring at cathode is

• 2H₂ (g) + O₂ → 2H₂O(l)

• O₂(g) + 2H₂O(l) + 4e^- → 4OH^-(aq)

• H⁺ +e^- → 1/2H₂

• H⁺(aq) + OH^- → H₂O(l)

Which of the following curve is in accordance with Freundlich adsorption isotherm?