Which of the following is a Lewis acid ? from Chemistry Equilibr

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511.

Which of the following is a Lewis acid ?

  • OH-

  • H+

  • F-

  • NH3


B.

H+

Lewis acid is any substance that can accept a pair of non- bonding electrons, such as the H+ ions. It is an electron pair acceptor.

Lewis base is any substance that can donate a pair of electrons.

OH-, F- and NH3 are Lewis base because they can donate a lone pair of electrons while H+ is a Lewis acid because it can accept a lone pair of electrons.


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512.

Which of the following is correct?

  • The pH of one litre solution containing 0.49 g of H2SO4 is 2.0

  • The conjugate base of H2S is S2-

  • BF3 is a Lewis base

  • Phenolphthalein is colourless in basic medium


513.

Which of the following is correct ?

  • Catalyst undergoes permanent chemical change

  • Particle size of solute in true solution is 10-3 m

  • Starch solution is a hydrosol

  • Hydrolysis of liquid ester in the presence of mineral acid is an example of heterogeneous catalysis reactions


514.

What is the equation for the equilibrium constant (Kc) for the following reaction?

12A(g) + 13B(g) T(K) 23C(g)

  • Kc = A12 B13C32

  • Kc = C32A2 B3

  • Kc = C23A12B13

  • Kc = C23A12+B13


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515.

A 0.1 aqueous solution of a weak acid is 2% ionised. If the ionic product of water is 1 x 10-4, the [OH-] is

  • 5 x 10-12 M

  • 2 x 10-3 M

  • 1 x 10-14 M

  • None of these


516.

Disperse phase and dispersion medium in butter are respectively

  • solid and liquid

  • liquid and solid

  • liquid and liquid

  • solid and solid


517.

9.2 g N2O4 is heated in a 1L vessel till equilibrium state is established

N2O4 (g)  2NO2 (g)

In equilibrium state 50% Np4 was dissociated, equilibrium constant will be (mol. wt. of N2O4 = 92)

  • 0.1

  • 0.4

  • 0.3

  • 0.2


518.

Solubility product of PbCl2 at 298 K is 1 x 10-6. At this temperature solubility of PbCl2 in mol/L is

  • (1 x 10-6)1/2

  • (1 x 10-6)1/3

  • (0.25 x 10-6)1/3

  • (2.5 x 10-6)1/2


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519.

Which of the following is the electron deficient molecule?

  • B2H6

  • C2H6

  • PH3

  • SiH4


520.

Equilibrium constants K1 and K2 for the following equilibria
NO (g) + 12O2  K1 NO2(g) and

2NO2(g) K2 2NO (g) + O2(g)

are related as

  • K2 = 1 K1

  • K2 = K12

  • K2 = K12

  • K2 =1K12


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