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 Multiple Choice QuestionsMultiple Choice Questions

101.

The stability of a lyophobic colloid is due to

  • adsorption of covalent molecules on the colloid

  • the size of the particles

  • the charge on the particles

  • Tyndall effect


102.

Which of the following cations will have minimum flocculation value for arsenic sulphide sol?

  • Na+

  • Mg2+

  • Ca2+

  • Al3+


103.

Adsorption theory is applicable for

  • homogeneous catalysis

  • heterogeneous catalysis

  • autocataylsis

  • induced catalysis


104.

All colloidal dispersions have

  • low osmotic pressure

  • no osmotic pressure

  • high osmotic pressure

  • very high osmotic pressure


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105.

Silver iodide is used for producing artificial rain because AgI

  • is easy to synthesize

  • has crystal structure similar to ice

  • is insoluble in water

  • is easy to spray at high altitude


106.

During the adsorption of a gas on the surface of a solid, which of the following is true?

  • G > 0, H < 0, S < 0

  • G < 0, H < 0, S < 0

  • G <0, H < 0, S > 0

  • G <0, H > 0, S < 0


107.

A crystalline solid X reacts with dil. HCl to liberate a gas Y. Y decolourises acidified KMnO4. When a gas 'Z' is slowly passed into an aqueous solution of Y, colloidal sulphur is obtained X and Z could be respectively

  • Na2S, SO3

  • Na2SO4, H2S

  • Na2SO3, H2S

  • Na2SO4, SO2


108.

Gold sol is not

  • a macromolecular colloid

  • a lyophobic colloid

  • a multimolecular colloid

  • negatively charged colloid


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109.

For Freundlich isotherm a graph of log x/m is plotted against log p. The slope of the line and its y-axis intercept, respectively corresponds to

  • 1n , k

  • log 1n , k

  • 1n , log k

  • log 1n, log k


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110.

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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