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Correct CHOICE is (c) Liquid in solid

For explanation I would say: A gel is a colloidal SYSTEM in which the DISPERSED PHASE is a liquid and the dispersion medium is a solid. Toothpaste, JAM, cheese, rubber and gelatin (animal protein) are some of the examples of colloidal systems which are gels.

Right choice is (a) 1 to 100 nm

The best I can EXPLAIN: A colloid is TYPICALLY a two-phase system consisting of a continuous phase (the dispersion MEDIUM) and dispersed phase (the particles or EMULSION droplets). The particle size of the dispersed phase typically ranges from 1 nanometre to 1 micrometre.

The correct answer is (d) ΔS > 0

Easiest EXPLANATION: Physisorption is reversible as the molecules of the adsorbate are HELD to the adsorbent by weak Van der Waals forces which can be broken easily. Physisorption is exothermic and so, ΔH is negative. Adsorption is a spontaneous PROCESS. In adsorption, the movement of the adsorbed MOLECULE is RESTRICTED. As a result the entropy change (ΔS) is negative.

The correct answer is (a) PARCHMENT paper

The explanation is: Centrifugation is a process which involves the USE of the centrifugal force for the sedimentation of heterogeneous MIXTURES with a centrifuge USED in industry and in laboratory SETTINGS. This process is used to separate two immiscible liquids. Particles of colloids are big enough to be blocked by parchment paper or animal membrane.

The correct option is (B) Digestion does not involve the process of emulsification

To explain: The digestion of fats in the intestines takes PLACE by the process of emulsification. A small amount of the fat REACTS with the alkaline SOLUTION present in the intestines to form a sodium SOAP.

The CORRECT answer is (d) Solid, alcohol

To explain I would say: A colloidal solution having alcohol as the DISPERSION medium and a solid substance as the dispersed PHASE is called an alcohol. For EXAMPLE: A colloidal solution of cellulose nitrate in ETHYL alcohol is an alcohol.

Right option is (c) Catalytic poison

The best explanation: A catalytic poison is a SUBSTANCE which destroys the activity of the catalyst even if it is PRESENT in trace AMOUNTS. Eg: In the MANUFACTURE of sulphuric acid by contact process, any arsenic impurity present in the reacting GASES will destroy the activity of vanadium pentoxide catalyst.

Correct ANSWER is (a) True

Explanation: In physisorption, there is no chemical bond between the ADSORBENT and ADSORBATE. They are held TOGETHER by Van der Waals forces. SINCE Van der Waals forces are universal and almost same for all gases, the adsorbent does not show specificity to a particular gas.

Right answer is (c) Van der Waals force

Best EXPLANATION: In physical adsorption, the MOLECULES of the adsorbate STICK to the surface of the adsorbent due to very weak forces which is known as Van der Waals force. Van der Waals force is SIMILAR to the forces that cause CONDENSATION of gas into liquid.

The correct choice is (c) Kalaazar

To explain I WOULD say: Most of the medicines used today are of COLLOIDAL forms as they are EASY to assimilate in the body. Colloidal antimony is usually used to cure EYE diseases and also Kalaazar(also called visceral LEISHMANIASIS).

Right option is (B) COLLOIDAL solution of ferric hydroxide

The best I can explain: Colloidal solution of ferric hydroxide (Fe(OH)3) is given to a PERSON suffering from ARSENIC poisoning. It is used as ferric hydroxide ADSORBS arsenic and this can be vomited out later.

Correct answer is (b) Zeolite

Easy EXPLANATION: The ZEOLITES used in catalytic cracking are chosen to GIVE high percentages of hydrocarbons with between 5 and 10 carbon atoms – particularly useful for petrol. The zeolite catalyst has sites which can remove a hydrogen from an ALKANE TOGETHER with the two electrons which bound it to the carbon.

Right choice is (d) Decreases with increase in TEMPERATURE

To ELABORATE: Physisorption is an exothermic process. According to Le-Chatelier’s PRINCIPLE, an exothermic reaction is favoured by a decrease in temperature. Therefore, the EXTENT of physisorption decreases on INCREASING temperature.

The correct option is (c) Chromium salts

The best I can explain: Tannin, obtained from PLANTS, is a mixture of polyhydroxy benzoic acids. It contains NEGATIVELY charged colloidal particles which make it useful for TANNING as animal hides contain POSITIVELY charged colloidal particles. Chromium salts can be used in place of tannin.

Correct choice is (c) C15H31COONa

To elaborate: To obtain a STABLE emulsion, sometimes, small quantities of certain other substances are added during its preparation. The substances thus added to STABILIZE the emulsions are CALLED emulsifiers or emulsifying agents.

Correct ANSWER is (a) Emulsions cannot be separated into their constituent liquids

Explanation: Emulsions can be separated into their constituent liquids by boiling, freezing, centrifuging, electrostatic PRECIPITATION by adding large AMOUNTS of the electrolyte to precipitate out the dispersed PHASE or by chemical destruction of the emulsifying agent.

Correct choice is (a) Starch SOLUTION

The explanation is: Starch solution is most STABLE AMONG the following because it is a lyophilic colloid and the SOLUTIONS are highly stable due to the high interaction between the dispersed phase and the dispersion medium.

Correct CHOICE is (c) Gum

Explanation: Some substances at low concentration behave as true solutions. As the concentration of the SOLUTION increases, it turns to be a colloidal solution. These type of COLLOIDS are knows as associated solution. Soaps like sodium stearate potassium stearate and detergents are examples of associated colloids whereas gum is an example for LYOPHILIC colloids.

Right choice is (c) SILVER solution can form macro-molecular COLLOIDS

Best explanation: Macro-molecules DISSOLVE in a suitable solvents, gives rise to PARTICLES of colloidal SIZE. These are normally of lyophilic type and silver solution is an example for lyophobic and multi-molecular colloids.

The correct choice is (a) Decreasing Ea

Easy EXPLANATION: A CATALYST lowers the activation ENERGY and so more PARTICLES can attain activation energy, thus a faster rate of reaction. Only a small amount of catalyst is required. Increasing the amount of catalyst used will not increase the rates of reaction beyond a certain POINT.

The correct choice is (a) True

For explanation I would say: Based on the nature of DISPERSED phase, colloids are classified into multi-molecular, macro-molecular and associated colloids. In multi-molecular colloids a large NUMBER of atoms aggregate to form a particle of colloidal size, in macro-molecular colloids molecules dissolve in SUITABLE solvents and GIVE rise to particles of colloidal size. Colloids which behave as a normal strong ELECTROLYTE at low concentration but exhibits colloidal properties at higher concentration are known as associated colloids.

The correct answer is (a) CHEMISORPTION is STRONGER than physisorption

Explanation: Chemisorption is stronger than physisorption. Chemisorption involves the FORMING of a chemical bond between the ADSORBENT and the adsorbate whereas in physisorption, the molecules are held together by weak Van DER Waal’s forces. Therefore, chemisorption is stronger.

Right choice is (d) Clouds are not a colloidal system

The explanation is: When it is COLD, the MOISTURE in the air condenses on the surface of dust particles, forming tiny droplets. These droplets are colloidal in nature and form a blanket of fog or mist in the atmosphere. Clouds are colloidal SYSTEMS as they are aerosols CONSISTING of WATER droplets suspended in air.

Right option is (c) NaCl solution

Easy explanation: Gold solution, SULPHUR solution and blood are colloids in which the dispersed phase has very low AFFINITY for the dispersion medium and once the dispersed phase and dispersion medium are SEPARATED we cannot get the solution directly by remixing the two phases. THEREFORE they are CATEGORIZED under lyophobic colloids.

Right answer is (d) 10^-7 m

For explanation: Colloidal state of matter is, therefore, a state in which the size of the particles is such (1 to 1000 NM) that they can pass through FILTER paper but not through ANIMAL or VEGETABLE membrane. Thus, every substance can be brought into the colloidal state by adopting suitable methods.

Right choice is (c) Homogeneous catalysis

Explanation: A CATALYST is a SUBSTANCE which INCREASES the RATE of reaction but itself does not undergo any chemical change during the reaction. In homogeneous catalysis, the REACTANTS and catalyst are in the same phase (i.e. liquid or gas).

Right choice is (a) Photography

For explanation I would say: A colloidal SOLUTION of silver bromide in gelatine is used in photographical devices. The colloidal solution is applied on glass PLATES, CELLULOID films or paper to FORM sensitive plates in photography.

Correct choice is (b) A large number of atoms AGGREGATE to form a particle of colloidal size

To elaborate: In this type of colloidal solution, a large number of atoms or SMALL molecules aggregate to form a particle of colloidal size, these are normally of LYOPHOBIC type. Starch solution is an EXAMPLE of lyophilic colloids and hence is not an example for multi-molecular colloids.

Right choice is (a) 400

For explanation I WOULD say: The AMOUNT of the intermediate formed is NOTHING but the difference in the compounds used.

Given,

Initial amount = 300

Final amount = 700

Hence, the amount of intermediate formed is 700 – 300 = 400.

The correct OPTION is (c) Catalyst lowers the ENERGY of activation of the forward REACTION without affecting the energy or activation of the backward reaction

The explanation is: A catalyst PROVIDES an alternate pathway for the reaction that has lower activation energy. When activation energy is lower, more reactant particles have ENOUGH energy to react and so the reaction occurs faster.

The correct choice is (B) Lyophobic colloids

Explanation: Lyophobic colloids such as metal solutions like gold and silver solution, sulphur solution and blood cannot be prepared DIRECTLY by mixing. These are prepared by special methods and are irreversible in NATURE. Once the dispersed phase and medium are separated it is not POSSIBLE to get the solution by remixing the two phases.

Right answer is (a) Colloidal solution of GRAPHITE in water

The explanation is: Aquadag is the TRADE name of a colloidal solution of graphite in water. It is mainly USED as a CONDUCTOR and a lubricant. On the other hand, a colloidal solution of oil in water is called as “oildag” and a colloidal solution of gold in water is called “PURPLE of Cassius”.

The correct option is (d) Milk

Easiest explanation: In an EMULSION of water-in-oil (w/o), water is the dispersed phase and oil is the dispersion medium. Cod LIVER oil, BUTTER and cold cream are all examples of the water-in-oil type of emulsions.

Correct option is (a) True

Best EXPLANATION: Based on the INTERACTION between the dispersed and dispersion medium, COLLOIDS are classified into two types, LYOPHILIC and lyophobic colloids. Lyophilic colloids are those in which the dispersed PHASE has high affinity for dispersion medium and lyophobic colloids are those in which the dispersed phase has no affinity or least affinity for the dispersion medium.

The correct option is (b) HETEROGENEOUS mixture

To explain I WOULD say: Colloidal sols form heterogeneous mixtures consisting of particles of dispersed phase and the dispersion MEDIUM. The dispersed particles are spread evenly throughout the dispersion medium, which can be a SOLID, liquid, or GAS.

Right OPTION is (a) Different DIAMETERS of colloidal gold particles

To explain I would SAY: Colloidal SOLUTIONS of gold prepared by different methods are of different colours because of different diameters of colloidal gold particles. The colour of colloidal solutions depends UPON the size of the colloidal particles.

Right option is (B) Adsorption

Easiest explanation: Adsorption is the PROCESS which involves the ACCUMULATION of the molecules of a substance in higher concentration on the SURFACE of a solid or a liquid. For example, GASSES are adsorbed on the surface of charcoal.

The correct answer is (a) Catalyst is not INVOLVED in the REACTION

The EXPLANATION: Catalyst is a substance which increases or decreases the rate of reaction but itself does not undergo any chemical change during the reaction. Catalysts that increase the rate are CALLED positive catalysts and the catalysts that decrease the rate are called NEGATIVE catalysts.

Correct CHOICE is (c) It is used as an EYE lotion

The EXPLANATION: Argyrol is an antiseptic containing solutions of MILD silver proteins. It is made up of a silver sol and is used as an eye lotion majorly to treat gonorrhoeal blindness and other PATHOGENIC infections in the eyes of new-born infants.

The correct choice is (b) Silver iodide

Explanation: Clouds can be made to cause rain by spraying oppositely charged colloidal DUST, SAND particles or precipitates of silver iodide over them. This causes a neutralisation reaction between the two colloids and result in the coagulation of WATER droplets which COME down as rain.

Correct OPTION is (d) Casein

The explanation: The emulsifier or emulsifying AGENT PRESENT in DAIRY emulsions is Casein. Casein is a slow-digesting dairy PROTEIN that people often take as a supplement.The most common form of casein is sodium caseinate.

Correct option is (a) True

The explanation is: Soaps are sodium or POTASSIUM SALTS of higher fatty acids, for example, sodium palmitate (C15H31COONa), sodium stearate (C17H35COONa), ETC. A molecule of soap CONSISTS of two parts, the hydrophobic part (soluble in oil) and the hydrophilic part (soluble in water).

The correct CHOICE is (b) False

Explanation: A catalytic promoter is a substance which increases the activity of the CATALYST but itself does not act as a catalyst. Eg: In the MANUFACTURE of ammonia by Haber’s PROCESS, Molybdenum ACTS as a catalytic promoter for the iron catalyst.

Right choice is (d) Occurs at low temperature

Explanation: CHEMISORPTION is a kind of adsorption that involves a chemical reaction between the adsorbent and adsorbate, resulting in the FORMATION of a chemical bond between the two. Since a bond is to be formed, chemisorption is highly DEPENDENT on the reactants(adsorbate and adsorbent) and has a large HEAT of adsorption. Also, since it involves bond formation, it cannot be multi-layered. Chemisorption is FAVOURED to occur at high temperature.

Right answer is (b) Increase in temperature

The explanation: PHYSISORPTION occurs due to Van der Waals forces. On increasing the temperature, the adsorbate can split into ATOMS and form chemical bonds with the adsorbent and HENCE, cause CHEMISORPTION.

Correct answer is (a) True

Easiest explanation: Colloidal particles present in sewage such as dirt, MUD have an electrical charge. When sewage is through plates at a HIGH potential, the colloidal particles COAGULATE DUE to electrophoresis and GETS removed.