Chapter 12

When a chalk stick is dipped in ink, then (a) the coloured pigments in the ink get absorbed in the chalk. (b) the solvent get adsorbed at the surface of chalk. (c) inside of the chalk will remain as white while the surface will have coloured pigments. (d) inside of the chalk will have coloured pigments while the surface will remain white.

Desorption of a gas from metal surface follows first-order kinetics. The rate constant of desorption can be given by Arrhenius equation. If the desorption of hydrogen on manganese is found to increase 10 times on increasing the temperature from 600 to \(1000 \mathrm{~K}\), the activation energy of desorption is (a) \(6.0 \mathrm{kcal} / \mathrm{mol}\) (b) \(6.9 \mathrm{kcal} / \mathrm{mol}\) (c) \(3.0 \mathrm{kcal} / \mathrm{mol}\) (d) \(57.4 \mathrm{kcal} / \mathrm{mol}\)

The rate of chemisorption (a) decreases with increase of pressure (b) is independent of pressure (c) is maximum at one atmospheric pressure (d) increases with increase of pressure

Chromatography is a technique based on (a) Solubilities of solute (b) Adsorption of solute (c) Chemical adsorption followed by dispersion (d) Differential adsorption of different constituents of a mixture

The following information is available for the reaction: \(\mathrm{R} \rightarrow \mathrm{P}\) : \(\mathrm{R} \longrightarrow \mathrm{P} ; \quad\) rate \(=r_{1}\) \(\mathrm{R} \stackrel{\mathrm{A}}{\longrightarrow} \mathrm{P} ; \quad\) rate \(=r_{2}\) \(\mathrm{R} \stackrel{\mathrm{B}}{\longrightarrow} \mathrm{P} ; \quad\) rate \(=r_{3}\) \(\mathrm{R} \stackrel{\mathrm{c}}{\longrightarrow} \mathrm{P} ; \quad\) rate \(=r_{4}\) \(\mathrm{R} \stackrel{\mathrm{D}}{\longrightarrow} \mathrm{P} ; \quad\) rate \(=r_{5}\) \(\mathrm{R} \stackrel{\mathrm{A}+\mathrm{C}}{\longrightarrow} \mathrm{P} ; \quad\) rate \(=r_{6}\) \(\mathrm{R} \stackrel{\mathrm{A}+\mathrm{D}}{\longrightarrow} \mathrm{P} ; \quad\) rate \(=r_{7}\) If \(r_{3}

The nature of bonding forces in adsorption is (a) purely physical like Vander Waal's force (b) purely chemical (c) both, physical and chemical, always (d) none of these

Which of the following statements is false for catalyst? (a) A catalyst initiates the reaction. (b) It does not alter the position of equilibrium in a reversible reaction. (c) A catalyst remains unchanged in quantity and composition at the end of reaction. (d) Catalysts are sometimes very specific in respect of a reaction.

A catalytic poison renders the catalyst ineffective because (a) it is preferentially adsorbed on the catalyst. (b) it adsorbs the molecules of the reactants. (c) it combines chemically with the catalyst. (d) it combines with one of the reactant.

Sorption is the term used when (a) only adsorption takes place (b) only absorption takes place (c) adsorption and absorption occur simultaneously (d) desorption takes place

Which of the following statements about a catalyst is true? (a) A catalyst accelerates reaction by bringing down the free energy of activation. (b) A catalyst does not take part in the reaction mechanism. (c) A catalyst makes the reaction more feasible by making the \(\Delta G^{\circ}\) more negative. (d) A catalyst makes the equilibrium constant of the reaction more favourable for the forward reaction.

In the Freundlich adsorption isotherm, the slope of the straight line graph between \(\log (x / m)\) and \(\log P\) for the adsorption of a gas on solid is (a) \(k\) (b) \(\log k\) (c) \(n\) (d) \(1 / n\)

Which of the following is not true with respect to a catalyst? (a) A catalyst increases the rate of a reaction while inhibitor decreases the reaction rate. (b) A promoter cannot catalyse the reaction on its own without the presence of a catalyst. (c) The activity of enzyme catalyst increases in the presence of metal ions like \(\mathrm{Mn}^{2+}, \mathrm{Co}^{2+}\), etc. (d) When a solid catalyst is used for gaseous reaction, energy released in physisorption increases the rate of a reaction.

Which of the following is not a property of hydrophilic sol? (a) High concentration of dispersed phase can be easily attained. (b) Coagulation is reversible. (c) Viscosity and surface tension are nearly as that of water. (d) The charge on the particles may depend on the \(\mathrm{pH}\) value; it may be positive, negative or even zero.

The enthalpy of adsorption in physisorption lies in the range (a) \(-(40-400) \mathrm{kJ} / \mathrm{mol}\) (b) \(-(80-240) \mathrm{kJ} / \mathrm{mol}\) (c) \(-(20-40) \mathrm{kJ} / \mathrm{mol}\) (d) \(-(1-10) \mathrm{kJ} / \mathrm{mol}\)

Which metal sol (dispersion medium being water) cannot be prepared by Bredig's arc method? (a) \(\mathrm{K}\) (b) \(\mathrm{Cu}\) (c) \(\mathrm{Au}\) (d) \(\mathrm{Pt}\)

How many layers are adsorbed in chemical adsorption? (a) 1 (b) 2 (c) 3 (d) 1 or more

When some special substances such as protein particles, blood corpuscles, etc. are separated by a permeable membrane. The process is called (a) Dialysis (b) Diffusion (c) Exosmosis (d) Endosmosis

The simplest way to check whether a system is colloidal is by (a) Tyndall effect (b) Brownian movement (c) Electro dialysis (d) Finding out particle size

When a lyophobic colloidal solution is observed in Tyndall effect, we can see (a) size of colloidal particles (b) light scattered by colloidal particles (c) shape of colloidal particles (d) size of particles of dispersion medium

Identify the statement which is correct with respect to surface phenomenon. (a) Osmotic pressure of rubber sol will be same as that of sucrose solution having same mass mixed in same mass of water. (b) A gas may show physisorption at low temperature and chemisorption at high temperature. (c) Soap sol of sodium palmitate will coagulate near cathode in electrophoresis. (d) Gold sol on mixing with starch sol causes stabilization of starch sol.

Which of the following types of metals make the most efficient catalysts? (a) Transition metals (b) Alkali metals (c) Alkaline earth metals (d) Radioactive metals

Which of the following reaction is not used in the preparation of colloidal solution? (a) \(2 \mathrm{H}_{2} \mathrm{~S}+\mathrm{SO}_{2} \rightarrow 3 \mathrm{~S}+2 \mathrm{H}_{2} \mathrm{O}\) (b) \(2 \mathrm{Mg}+\mathrm{CO}_{2} \rightarrow 2 \mathrm{Mg} \mathrm{O}+\mathrm{C}\) (c) \(\mathrm{FeCl}_{3}+3 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Fe}(\mathrm{OH})_{3}+3 \mathrm{HCl}\) (d) \(2 \mathrm{AuCl}_{3}+3 \mathrm{SnCl}_{2} \rightarrow 2 \mathrm{Au}+3 \mathrm{SnCl}_{4}\)

A quantity of \(1.9 \times 10^{-4} \mathrm{~g}\) of the metal having density \(19 \mathrm{~g} / \mathrm{ml}\) is dispersed in 11 of water to give a sol having spherical metal particles of radius \(10 \mathrm{~nm} .\) The approximate number of metal sol particles per \(\mathrm{cm}^{3}\) of the sol is (a) \(2.35 \times 10^{9}\) (b) \(4 \times 10^{10}\) (c) \(1.9 \times 10^{9}\) (d) \(2.8 \times 10^{9}\)

TEL minimizes the knocking effect when mixed with petrol. It acts as (a) Positive catalyst (b) Negative catalyst (c) Auto-catalyst (d) Induced catalyst

Platinized asbestos is used as a catalyst in the manufacture of \(\mathrm{H}_{2} \mathrm{SO}_{4}\). It is an example of (a) Homogeneous catalyst (b) Heterogeneous catalyst (c) Auto-catalyst (d) Induced catalyst

The correct match is $$ \begin{array}{ll} \hline \text { Column I } & \text { Column II } \\ \hline \text { (1) Coagulation } & \text { (P) } \begin{array}{l} \text { Scattering of } \\ \text { light } \end{array} \\ \text { (2) Peptization } & \text { (Q) } \begin{array}{l} \text { Purification } \\ \text { of colloidal } \\ \text { solution } \end{array} \\ \begin{array}{ll} \text { (3) } \text { Tyndall } \\ \text { effect } \end{array} & \text { (R) } \begin{array}{l} \text { Addition of an } \\ \text { electrolyte } \end{array} \\ \text { (4) Dialysis } & \text { (S) } \begin{array}{l} \text { Precipitation } \\ \text { of colloidal } \\ \text { solution } \end{array} \\ \hline \end{array} $$ $$\begin{array}{llll}1 & 2 & 3 & 4\end{array}$$ (a) \(\begin{array}{llll}\mathrm{P} & \mathrm{Q} & \mathrm{R} & \mathrm{S}\end{array}\) (b) \(\begin{array}{llll}\mathrm{S} & \mathrm{R} & \mathrm{P} & \mathrm{Q}\end{array}\) (c) \(\begin{array}{llll}\mathrm{R} & \mathrm{S} & \mathrm{Q} & \mathrm{P}\end{array}\) (d) Q \(\mathrm{R} \quad \mathrm{P} \quad \mathrm{S}\)

In the Ostwald's process for the manufacture of \(\mathrm{HNO}_{3}\), the catalyst used is (a) \(\mathrm{Fe}\) (b) \(\mathrm{Pt}\) (c) \(\mathrm{V}_{2} \mathrm{O}_{5}\) (d) Mo

In a reversible reaction, a catalyst (a) increases the rate of forward reaction only (b) increases the rate of forward reaction to a greater extent that of the backward reaction (c) increases the rate of forward reaction and decreases that of the backward reaction (d) increases the rate of forward and backward reaction by the same factor.

Air can oxidize sodium sulphate in aqueous solution but cannot do so in the case of sodium arsenite. If, however, air is passed through a solution containing both sodium sulphite and sodium arsenite then both are oxidized. This is an example of (a) Positive catalysis (b) Negative catalysis (c) Induced catalysis (d) Auto catalysis

A catalyst is a substance which (a) increases the equilibrium concentration of the product. (b) changes the equilibrium constant of the reaction. (c) shortens the time to reach equilibrium. (d) supplies energy to the reaction.

The work of enzymes in living system is (a) oxygen transfer (b) to provide immunity (c) to catalyse biochemical reactions (d) to provide energy

In the case of auto catalysis (a) reactant catalyses (b) heat produced in the reaction catalyses (c) product catalyses (d) solvent catalyses

Zeolites are used as catalyst in (a) Petrochemical industries during cracking (b) In the preparation of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (c) In the hydrolysis of ester (d) All

Butter is a colloid formed when (a) liquid fat is dispersed in liquid fat (b) liquid fat is dispersed in water (c) water is dispersed in liquid fat (d) solid fat is dispersed in water

Sulphur sol contains (a) Discrete sulphur atoms (b) Discrete sulphur molecules (c) Water dispersed in solid sulphur (d) Large aggregates of sulphur molecules

When freshly precipitated \(\mathrm{Fe}(\mathrm{OH})_{3}\) is boiled with water in the presence of few drops of dil. HCl, a hydrated ferric oxide sol is obtained. The method is termed as (a) Electro dispersion (b) Peptization (c) Ultra filtration (d) Dialysis

Bleeding is stopped by application of ferric chloride. This is because (a) the blood starts flowing in opposite direction. (b) the ferric chloride seals the blood vessel. (c) the blood reacts and forms a solid which seals the blood vessel. (d) the blood is coagulated and thus, the blood vessel is sealed.

\(\mathrm{Fe}^{3+}\) ions coagulate blood. This shows that blood contains colloidal particles bearing (a) negative charge (b) positive charge (c) no charge (d) either positive or negative charge

Gold number is a measure of (a) the amount of gold present in the colloidal solution. (b) the amount of gold required to break the colloid. (c) the amount of gold required to protect the colloid. (d) the protective power of lyophilic colloid.

To coagulate gelatin sol, which of the following is most effective? (a) \(\mathrm{NaCl}\) (b) \(\mathrm{Na}_{3} \mathrm{PO}_{4}\) (c) \(\mathrm{AlCl}_{3}\) (d) Alcohol

The potential difference between the fixed charged layer and the diffused layer having opposite charge is called (a) Colloidal potential (b) Zeta potential (c) Electrostatic potential (d) Electrode potential

An examples of micelle is (a) \(\mathrm{As}_{2} \mathrm{O}_{3}\) solution (b) Ruby glass (c) \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) solution (d) Concentrated sodium stearate solution

A freshly prepared \(\mathrm{Fe}(\mathrm{OH})_{3}\) precipitate is peptized by adding \(\mathrm{FeCl}_{3}\) solution. The charge on the colloidal particle is due to preferential absorption of (a) \(\mathrm{Cl}\) ions (b) \(\mathrm{Fe}^{\text {th }}\) ions (c) \(\mathrm{OH}^{-}\) ions (d) \(\mathrm{H}^{+}\) ions

Among the following, which is the correct statement about milk? (a) Milk is an emulsion of liquid fat in water (b) Milk in emulsion of protein in water (c) Milk is stabilized by protein (d) Milk is stabilized by fat

Substances whose solutions can readily diffuse through animal membranes are called (a) Colloids (b) Crystalloids (c) Electrolytes (d) Non-clectrolytes

The size of the colloidal particles is in between (a) \(10^{-7}\) and \(10^{-9} \mathrm{~cm}\) (b) \(10^{-9}\) and \(10^{-11} \mathrm{~cm}\) (c) \(10^{-4}\) and \(10^{-7} \mathrm{~cm}\) (d) \(10^{-2}\) and \(10^{-3} \mathrm{~cm}\)

If dispersed phase is liquid and the dispersion medium is solid, the colloid is known as (a) sol (b) gel (c) emulsion (d) foam

An emulsion is a colloidal solution consisting of (a) two solids (b) two liquids (c) two gases (d) one solid and one liquid

Which of the following substance give a positively charged sol? (a) Gold (b) Arsenious sulphide (c) Starch (d) Ferric hydroxide

Blood may be purified by (a) Dialysis (b) Electro osmosis (c) Coagulation (d) Filtration