Surface Chemistry

Which of these does not act as a good adsorbent?

Correct! Wrong!

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Water is a good solvent and not an adsorbent, as its molecules on the surface do not have unbalanced/residual forces.

Zeolites are widely used in all but one of the options given below. Which one is that?

Correct! Wrong!

To retard rusting of machines, glycerol 'poison catalyst' is used, and not zeolite.

____is used as adsorbent in refining petroleum and vegetable oil

Correct! Wrong!

Correct choice is option B.

The remaining traces of air present in a container can be absorbed by substance X from a vessel that is evacuated by a vacuum pump to give a very high vacuum. What is the substance X?

Correct! Wrong!

Option C is correct. Charcoal is used to remove the traces of air remaining even after using vacuum pump. Charcoal is more effective as absorbent. It provides higher vacuum than the vacuum pump.

Emulsions can be diluted by using ____ .

Correct! Wrong!

Emulsions can be diluted by using dispersion medium.

____ is a positively charged sol.

Correct! Wrong!

Hydrated ferric oxide is a positively charged sol. Charcoal, starch and gums are negatively charged sols.

The critical micelle concentration for soaps is ____ .

Correct! Wrong!

The critical micelle concentration for soaps is 10-4 to 10-3 mol L-1.

One of the options does not belong to enzymes. Identify.

Correct! Wrong!

Enzymes are proteins, not vitamins of high molecular mass.

The phenomenon of Tyndall effect was first observed by ____ .

Correct! Wrong!

The phenomenon of Tyndall effect was first observed by Faraday and later studied in detail by Tyndall.

An enzyme converts proteins to peptides in the stomach. Which one?

Correct! Wrong!

In the stomach, pepsin enzyme converts proteins to peptides.

At ____ temperature, the easily liquefiable gases are physisorbed.

Correct! Wrong!

Easily liquefiable gases with higher critical temperature are readily adsorbed, as Van der Waal forces are stronger near the critical temperature. Example: 1 g of activated charcoal adsorbs more sulphur dioxide (critical temperature 630 K) than methane (critical temperature 190 K).

In physisorption, accumulation of gas on the surface of a solid occurs on account of ____.

Correct! Wrong!

In physisorption, accumulation of gas on the surface of a solid occurs on account of weak Van der Waals forces. This is a practically established using modern techniques such as Photo Electron Spectroscopy and Auger Electron Spectroscopy for investigating surfaces and nature of bonding during adsorption.

The essential difference between a solution and a colloid depends on ____ .

Correct! Wrong!

The essential difference between a solution and a colloid depends on size of particle. Solutions have particle size less than 1nm, while colloids have particle size in the range of 1-1000nm.

The process of peptization involves:

Correct! Wrong!

The peptization process involves the disintegration of the precipitates such that the size of the resulting particles falls in the colloidal range.

Chromatography is a technique based on ____.

Correct! Wrong!

Option D is the correct principle.

_____is wrong about Zeolite.

Correct! Wrong!

'They cannot be synthesized for catalytic activities' is incorrect. Zeolites are found in nature as well as can be synthesized for catalytic activities.

Which of the following options are related to catalysis?

Correct! Wrong!

The activity of a catalyst depends on chemisorption as reactant. Molecules/ atoms must get adsorbed just strong enough on the surface of the catalyst, to become active. If the reactant molecules are strongly held, then other molecules will have no space on the surface of the catalyst. Only when the first set of molecules leave, the next set of molecules can react.

Inversion of cane sugar takes place in the presence of which of the following enzymes?

Correct! Wrong!

As the name suggests, invertase is used for inversion of cane sugar into glucose and fructose.

Certain substances behave as normal strong electrolytes at low concentrations, but exhibit colloidal behaviour at high concentrations. Surface active agents ____ belong to this category.

Correct! Wrong!

Soaps and detergents form associated colloids above critical micelle concentration and Kraft's temperature.

The colloidal particles show Tyndall effect due to ______________ .

Correct! Wrong!

The colloidal particles show Tyndall effect due to scattering of light. The phenomenon of scattering of light by colloidal particles as a result of which the path of the beam becomes visible is called Tyndall effect.

____enzyme is responsible for conversion of milk into curd

Correct! Wrong!

When a little curd is added to milk, the lacto bacilli enzyme present in curd converts the entire milk into curd.

Noble gases have different degrees of adsorption at different temperatures. This property is used to separate them. Which substance is used as adsorbent?

Correct! Wrong!

Option A gives the correct answer.

Which fact about chemisorption is not true?

Correct! Wrong!

As the forces of attraction existing between adsorbent and adsorbate are very strong in chemisorption, it cannot be easily reversed.

Activated charcoal, activated alumina or silica gel is not used in one of the processes given below. Which one?

Correct! Wrong!

Option A gives the right answer. Zeolite is used for softening of water. Zeolite , which is sodium aluminosilicate, exchanges its Na+ ions with Ca2+ and Mg2+ of hard water. This exchange of ions is known as ‘exchange adsorption’. For demineralization of water this method is used.

Argyrol is a ______________ .

Correct! Wrong!

Argyrol is a colloidal sol of silver. It is used as an eye lotion.

Cod liver oil is an emulsion of ____ .

Correct! Wrong!

Cod liver oil is an emulsion of water in oil. Here, water is the dispersed phase and oil is the dispersion medium.

According to the theory of heterogeneous catalysis, which of the following statement is not correct?

Correct! Wrong!

The intermediate compound formed is desorbed from the catalyst surface. Desorption is the process of removing an adsorbed substance from the surface on which it is adsorbed. Absorption describes a process when adsorption and absorption take place simultaneously.

Which of the following is the reason for the air to become dry in the presence of silica gel?

Correct! Wrong!

Silica gel is a good adsorbent and adsorbs water content of the air.

This adsorbent is used to remove moisture and control humidity. Select the option with correct adsorbent.

Correct! Wrong!

Option A is correct.

The most effective electrolyte in the coagulation of gold sol is ____.

Correct! Wrong!

The most effective electrolyte in the coagulation of gold sol is MgCl2. Since gold sol is negatively charged, the effective electrolyte for coagulation must be positively charged with high valency. Mg2+ ion is the effective electrolyte in the coagulation of gold sol.

Class 12th Chemistry - 5 Surface Chemistry MCQs
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Class 12th Chemistry - 5 Surface Chemistry MCQs