Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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


22.

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


23.

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


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24.

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

  • NaCl

  • Na2S

  • Na2SO4

  • Na3PO4


A.

NaCl

According to Hardy - Schulze rule. Flocculation value (FV)∝1Coagulation power.

Since, coagulationg power is direct us related to valences of coagulating ion.

Thus, FV ∝ 1valency of flocculating ion electrolyte.

Hence, greater the valency of coagulating ion, lower will be the flocculating value and vice versa. As for the given positively charged sol, negative ion would be required for coagulation thus, for the given amons the coagulation power will be PO43-< SO42-= S2- < Cl- or flocculating but coagulating value would be in an order of  Cl- > S2- =  SO42->PO43-.Hence, NaCl will have the maximum flocculating value for the given positively charged sol.


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25.

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


26.

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

  • MA3B - Square planar

  • MA2B2 - tetrahedral

  • MABCD- saquare planar

  • MABCD- tetrahedral


27.

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

  • [Xe]4f8

  • [Xe]4f7

  • [Xe]4f7 5d16s2

  • [Xe]4f7 5d1


28.

MSO4 NH4OH XWhite ExcessNH4OH YH2S Z.Here, M and Z are

  • Cu, ZnS

  • Zn, ZnS

  • Fe, FeS

  • Al, Al2S3


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29.

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)


30.

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


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