In the reaction,Fe(OH)3 (s) ⇌ Fe3+ (aq) + 3OH- (a

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

The number of oxygen atoms in 4.4gm of CO2 is

  • 1.2 × 1023

  • 6 × 1022

  • 6 × 1023

  • 12 × 1023


2.

If the bond energies of H-H, Br-Br and H-Br are 433, 192 and 364 kJ mol-1 respectively, then H° for the reaction-

H2 (g) + Br2 (g) → 2HBr (g) is

  • -261 kJ

  • +103 kJ

  • +261 kJ

  • -103 kJ


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3.

In the reaction,

Fe(OH)3 (s)  Fe3+ (aq) + 3OH- (aq), if the concentration of OH- ions is decreased by 14 times, then the equilibrium concentration of Fe3+ will increase by

  • 8 times

  • 16 times

  • 64 times

  • 4 times


C.

64 times

Given,

Fe(OH)3 (s)  Fe3+ (aq) + 3OH- (aq)

Keq[Fe3+] [OH-]3[Fe(OH)3] = [Fe3+] [OH-]31

When [OH-] is decreased by 14 times, K becomes 

Keq = [Fe3+14.[OH]3

     = [Fe3+164[OH-]3

To keep the value of Keq constant, the [Fe3+] must be increased by 64 times so that Keq remains as such.

Keq = 64 × 164 [Fe3+][OH-]3

      = [Fe3+] [OH-]3


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4.

The correct statement regarding entropy is

  • at absolute zero temperature, entropy of a perfectly crystalline solid is zero

  • at absolute zero temperature, the entropy of a perfectly crystalline substance is positive

  • at absolute zero temperature, the entropy of all crystalline substances is zero

  • at 0°C, the entropy of a perfect crystalline solid is zero


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5.

Equilibrium constants K1 and K2 for the following equilibria,

I. NO (g) + 12 O2 (g)  NO2 (g)

II. 2NO2 (g)  2NO (g) + O2 (g) are related as

  • K1K2

  • K21K1

  • K1 = 2K2

  • K21K12


6.

The shape of XeFis

  • square planar

  • distorted octahedral

  • square pyramidal

  • pyramidal


7.

CO is a stronger ligand than Cl-, because

  • CO is a neutral molecule

  • CO has π-bonds

  • CO is poisonous

  • CO is more reactive


8.

Which of the following sequence is correct regarding field strength of ligands as per spectrochemical series?

  • SCN- < F- < CN- < CO

  • F- < SCN- < CN- < CO

  • CN- < F- < CO < SCN-

  • SCN- < CO < F- < CN-


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9.

A liquid can exist only

  • between triple and critical points

  • at any temperature above melting point

  • between melting and critical points

  • between boiling and melting points


10.

The energy of electron in the nth Bohr orbit of H-atom is

  • -13.6n2 eV

  • -13.6n eV

  • -13.6n4 eV

  • -13.6n3 eV


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