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Surface Chemistry · Question 7

NEET (UG) 2019Multiple CorrectMedium📈 Topic in 25% papers+4−1
1

Which mixture of the solution will lead to the formation of negatively charged colloidal [AgI] I- sol. ?

  1. 50 mL of 2 M AgNO3 + 50 mL of 1.5 M KI
  2. 50 mL of 0.1 M AgNO3 + 50 mL of 0.1 M KI
  3. 50 mL of 1 M AgNO3 + 50 mL of 1.5 M KI
  4. 50 mL of 1 M AgNO3 + 50 mL of 2 M KI

Answer

(3) 50 mL of 1 M AgNO3 + 50 mL of 1.5 M KI, (4) 50 mL of 1 M AgNO3 + 50 mL of 2 M KI

Solution

As per NCERT, when AgNO3 solution is added to excess KI solution, the precipitated AgI adsorbs I- ions and a negatively charged sol AgI/I- is formed. So KI must be in excess.

Millimoles = molarity volume (mL):

(1) AgNO3 = 2 50 = 100; KI = 1.5 50 = 75 Ag+ in excess, positive sol AgI/Ag+

(2) AgNO3 = 0.1 50 = 5; KI = 0.1 50 = 5 no excess ion, no charged sol

(3) AgNO3 = 1 50 = 50; KI = 1.5 50 = 75 I- in excess, negative sol

(4) AgNO3 = 1 50 = 50; KI = 2 50 = 100 I- in excess, negative sol

Mixtures (3) and (4) give the negatively charged [AgI] I- sol.

Answer: (3), (4)

Out of syllabusNEET (UG) 2019

Keep practising — Surface Chemistry

2

On which of the following properties does the coagulating power of an ion depend?

  1. The magnitude of the charge on the ion alone
  2. Size of the ion alone
  3. Both magnitude and sign of the charge on the ion
  4. The sign of charge on the ion alone
Out of syllabusNEET 2018
3

Which one of the following statements is not correct?

  1. The value of equilibrium constant is changed in the presence of a catalyst in the reaction at equilibrium.
  2. Enzymes catalyse mainly bio-chemical reactions.
  3. Coenzymes increase the catalytic activity of enzyme.
  4. Catalyst does not initiate any reaction.
Out of syllabusNEET 2017
4

Fog is a colloidal solution of

  1. solid in gas
  2. gas in gas
  3. liquid in gas
  4. gas in liquid.
Out of syllabusNEET 2016 (Phase 1)
5

Which one of the following characteristics is associated with adsorption?

  1. G and H are negative but S is positive.
  2. G and S are negative but H is positive.
  3. G is negative but H and S are positive.
  4. G, H and S all are negative.
Out of syllabusNEET 2016 (Phase 1)
6

The coagulation values in millimoles per litre of the electrolytes used for the coagulation of As2S3 are given below : I. (NaCl) = 52, II. (BaCl2) = 0.69, III. (MgSO4) = 0.22 The correct order of their coagulating power is

  1. I > II > III
  2. II > I > III
  3. III > II > I
  4. III > I > II
Out of syllabusNEET 2016 (Phase 2)
7

Which property of colloidal solution is independent of charge on the colloidal particles?

  1. Electro-osmosis
  2. Tyndall effect
  3. Coagulation
  4. Electrophoresis
Out of syllabusAIPMT 2015 (Cancelled)
8

Which of the following statements is correct for the spontaneous adsorption of a gas?

  1. is negative and, therefore, should be highly positive.
  2. is negative and, therefore, should be highly negative.
  3. is positive and, therefore, should be negative.
  4. is positive and, therefore, should also be highly positive.
AIPMT 2014
9

Which property of colloids is not dependent on the charge on colloidal particles?

  1. Coagulation
  2. Electrophoresis
  3. Electro-osmosis
  4. Tyndall effect
Out of syllabusAIPMT 2014
10

In Freundlich adsorption isotherm, the value of 1n is

  1. between 0 and 1 in all cases
  2. between 2 and 4 in all cases
  3. 1 in case of physical adsorption
  4. 1 in case of chemisorption.
Out of syllabusAIPMT 2012 (Prelims)
11

Which one of the following statements is incorrect about enzyme catalysis?

  1. Enzymes are mostly proteinous in nature.
  2. Enzyme action is specific.
  3. Enzymes are denatured by ultraviolet rays and at high temperature.
  4. Enzymes are least reactive at optimum temperature.
Out of syllabusAIPMT 2012 (Prelims)

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