CBSE Questions for Class 12 Engineering Chemistry Surface Chemistry Quiz 14 - MCQExams.com

In the manufacture of $$H_{2}SO_{4}$$ by contact process, the presence of $$As_{2}O_{3}$$ acts as
  • Catalytic promoter
  • Catalytic poison
  • Induced catalyst
  • Auto catalyst
TEL minimizes the knocking effect when mixed with petrol. It acts as
  • Positive catalyst
  • Negative catalyst
  • Auto-catalyst
  • Induced catalyst
The decomposition of $$H_{2}O_{2}$$ may be checked by adding a small quantity of phosphoric acid. It is an example of
  • Neutralization
  • Negative catalysis
  • Positive catalysis
  • Catalytic poisoning
When freshly precipitated $$Fe(OH)_{3}$$ 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:
  • Electro dispersion
  • Peptization
  • Ultra fltration
  • Dialysis
To coagulate gelatin sol, which of the following is most effective?
  • $$NaCl$$
  • $$Na_{3}PO_{4}$$
  • $$AlCl_{3}$$
  • $$Alcohol$$
Which among the following statements is false?
  • increase of pressure increases the amount of adsorption.
  • increase of temperature may decrease the amount of adsorption.
  • the adsorption may be monolayered or multilayered.
  • particle size of the adsorbent will not affect the amount of adsorption.
Among the following, which is the correct statement about milk?
  • Milk is an emulsion of liquid fat in water
  • Milk in emulsion of protein in water
  • Milk is stabilized by protein
  • Milk is stabilized by fat
$$Fe^{3+}$$ ions coagulate blood. This shows that blood contains colloidal particles bearing
  • negative charge
  • positive charge
  • no charge
  • either positive or negative charge
Butter is a colloid formed when
  • liquid fat is dispersed in liquid fat
  • liquid fat is dispersed in water
  • water is dispersed in liquid fat
  • solid fat is dispersed in water
Zeolites are used as catalyst in
  • Petrochemical industries during cracking
  • In the preparation of $$H_{2}SO_{4}$$
  • In the hydrolysis of ester
  • All
Peptization is a process of
  • precipitating the colloidal particles.
  • purifying the colloidal sol.
  • dispersing the precipitate into colloidal sol.
  • movement of colloidal particles towards the opposite charged electrodes.
Which is not correct for heterogeneous catalysis?
  • The catalyst decreases the energy of activation.
  • The surface of catalyst plays an important role.
  • The catalyst forms an intermediate with the reactants, at the surface.
  • There is no change in the energy of activation.
Sulphur sol contains
  • Discrete sulphur atoms
  • Discrete sulphur molecules
  • Water dispersed in solid sulphur
  • Large aggregates of sulphur molecules
A catalytic poison renders the catalyst ineffective because
  • it is preferentially adsorbed on the catalyst.
  • it adsorbs the molecules of the reactants.
  • it combines chemically with the catalyst.
  • it combines with one of the reactant.
Which of the following option(s) is/are correct regarding catalytic activity?
  • Conversion of proteins into amino acids by hydrolysis in intestine is catalysed by enzyme pancreatic trypsin.
  • In case of fever, the activity of bio-chemical catalyst gets adversely affected.
  • In heterogeneous catalysis, the reactants must get adsorbed reasonably strong on the catalyst surface but not so strongly that desorption of product becomes impossible.
  • In the decomposition of methyl urea, enzyme urease acts as a catalyst.
Regarding criteria of catalyst, which one of the following statements is not true?
  • The catalyst is unchanged chemically after the reaction.
  • A small quantity of catalyst is often sufficient to bring about a considerable amount of the reaction.
  • In reversible reaction, the catalyst alters the equilibrium position.
  • The catalyst alters the rate of reaction.
Which of the following statements is false for catalyst?
  • A catalyst initiates the reaction.
  • It does not alter the position of equilibrium in a reversible reaction.
  • A catalyst remains unchanged in quantity and composition at the end of reaction.
  • Catalysts are sometimes very specific in respect of a reaction.
Which of the following statements is incorrect about catalyst?
  • A catalyst catalyses a spontaneous chemical reaction.
  • A catalyst catalyses all chemical reaction, whether spontaneous or non-spontaneous.
  • A catalyst provides alternate path of chemical reaction.
  • A catalyst does not involve in a chemical reaction.
Which of the following is not true with respect to a catalyst?
  • A catalyst increases the rate of a reaction while inhibitor decreases the reaction rate.
  • A promoter cannot catalyse the reaction on its own without the presence of a catalyst.
  • The activity of enzyme catalyst increases in the presence of metal ions like $$Mn^{2+}$$, $$Co^{2+}$$, etc.
  • When a solid catalyst is used for gaseous reaction, energy released in physisorption increases the rate of a reaction.
The emulsifying agent in milk is
  • Lactic acid
  • Casein
  • Lactose
  • Fat
A catalyst is used 
  • Only for increasing the velocity of the reaction
  • For altering the velocity of the reaction
  • Only for decreasing the velocity of the reaction
  • All (a), (b) and (c) are correct
If the absorbate is held on a surface by weak van der Waal's forces the absorption process is called 
  • physical adsorption
  • chemical adsorption
  • heat of adsorption
  • enthalpy of adsorption
Which is the correct statement in case of milk
  • Milk is an emulsion of protein in water
  • Milk is an emulsion of fat in water
  • Milk is stablised by protein
  • Milk is stabiloised by fat
Which among the following statement is false ?
  • The adsorption may be monolayered or multilayered
  • Particle size of adsorbent will not affect the amount of adsorption
  • Increases of pressure increases amount of adsorption
  • Increases of temperature may decrease the amount of adsorption
Which of the following forms a colloidal solution ion water?
  • NaCl
  • Glucose
  • Starch
  • Barium nitrate
A reaction is catalysed by $$'X'$$. Here $$'X'$$
  • Decreases the rate constant of reaction
  • Does not affect the equilibrium constant of reaction
  • Decreases the enthalpy of reaction
  • Decreases the activation energy
When a freshly precipitated substance is converted into a colloidal solution with the help of a third substance, the process is known as
  • Coagulation
  • Peptization
  • Electrodispersion
  • Dialysis
When $$KClO_{3}$$ is heated, it decomposes into $$KCl+O_{2}$$. If some $$MnO_{2}$$ is added, the reaction goes much faster because
  • $$MnO_{2}$$ decomposes to give $$O_{2}$$
  • $$MnO_{2}$$ provides heat by reacting
  • Better contact is provided by $$MnO_{2}$$
  • $$MnO_{2}$$ acts as a catalyst
Colloidal solution cannot be obtained from two such substance which are
  • Insoluble in each other
  • In same physical state
  • In different physical state
  • None of these
In a reversible reaction, a catalyst will affect the rate of
  • Forward reaction
  • Reverse reaction
  • Forward and reverse reaction
  • Neither (a) nor (b)
The catalyst used in the lead chamber process of sulphuric acid manufacture is 
  • Platinum
  • Oxide of nitrogen
  • Nickel
  • Vanadium compounds
What is the role of a catalyst in a catalysed reaction? 
  • Lowers the activation energy
  • Increases the activation energy
  • Affects the free energy change
  • Affects the enthalpy change
The role of a catalyst in a reversible reaction is to 
  • Increase the rate of forward reaction
  • Decrease the rate of backward reaction
  • Alter the equilibrium constant of the reaction
  • Allow the equilibrium to be achieved quickly
In the following reaction the catalyst used is
1756056_103e6d33b565461d911a9e88b6fa0b08.PNG
  • $$Al_{2}O_{3}$$
  • $$Cr_{2}O_{3}$$
  • $$Cr_{2}O_{3}$$ and $$Al_{2}O_{3}$$
  • Zn dust
Which of the following reactions leads to the formation of a substance in the colloidal state
  • $$ Cu+HgCl_{2}\rightarrow CuCl_{2}+Hg $$
  • $$ 2HNO_{3}+3H_{2}S\rightarrow 3S+4H_{2}O+2NO $$
  • $$ 2Mg+CO_{2}\rightarrow 2MgO+C $$
  • $$ Cu+CuCl_{2}\rightarrow Cu_{2}Cl_{2} $$
When a catalyst is added to a system the
  • Value of equilibrium constant is decreased
  • The rate of forward reaction is increased and that of backward reaction is decreased
  • Equilibrium concentration are unchanged
  • Equilibrium concentration are increased
Which of the following is used as a catalyst in the manufacture of toluene from benzene with $$CH_{3}Cl?$$
  • Ni
  • Anhydrous $$AlCl_{3}$$
  • Pd
  • Pt
A catalyst 
  • Increases the free energy change in the reaction
  • Decreases the free energy change in the reaction
  • Does not increase or decrease the free energy change in the reaction
  • Can either increase or decrease the free energy change depending on what catalyst we use
Hydrolysis ethyl acetate is catalysed by aqueous
  • $$Na_{2}SO_{4}$$
  • $$K_{2}SO_{4}$$
  • $$H_{2}SO_{4}$$
  • $$BaSO_{4}$$
In which of the following reactions heterogeneous catalysis is involved?


(a) $$2 SO_{2}(g)+O_{2}(g) \quad \stackrel{NO(g)}{\longrightarrow} 2 SO_{3}(g)$$



(b) $$2 S
O_{2}(g) \stackrel{Pt(s)}{\longleftarrow} 2 S O_{3}(g)$$



(c) $$N_{2}(g)+3
H_{2}(g\stackrel{Fe(s)}{\longrightarrow} 2 N H_{3}(g)$$



(d) $$C
H_{3} C O O C H_{3}(l)+H_{2} O(l) \stackrel{H Cl}{\longrightarrow} C H_{3} C O
O H(a q)+C H_{3} O H(a q)$$
  • (b),(c)
  • (b),(c),(d)
  • (a), (b), (c)
  • (d)
Which of the following statements are correct about solid catalyst?
  • Same reactants may give different product by using different catalysts.
  • Catalyst does not change $$\Delta \mathrm{H}$$ of reaction.
  • Catalyst is required in large quantities to catalyse reactions.
  • Catalytic activity of a solid catalyst does not depend upon the strength of chemisorption.
Shape selective catalysis is that reaction which s catalysed :
  • By enzyme
  • by zeolite
  • by platinum
  • by Zeigler - Natta Catalyst
The method pf blood purification in human body is :
  • Electrophoresis
  • Electric osmosis
  • Dialysis
  • Coagulation
Bredigs arc method involves:
  • dispersion of metal
  • condensation of metal
  • dispersion as well as condensation
  • neither dispersion nor condensation
Which of the following is an example of aerosol?
  • Paint
  • Milk
  • Sponge
  • Cloud
Which of the following statement is not correct?
  • Physical adsorption is due to Vander Waal's forces
  • Physical adsorption is irreversible
  • Chemical adsorption increases with increase in temperature in temperature up to certain limit than decreases
  • Enthalpy of adsorption (|ΔH|)(|ΔH|) for a chemical adsorption is greater than that of physical adsorption
On adding $$AgNO_{3}$$ solution to $$KI$$ solution, a negatively charged collodial sol will be formed in which of the following conditions?
  • $$100\ mL$$ of $$0.1\ M\ AgNO_{3}+100\ mL$$ of $$0.1\ M\ KI$$
  • $$100\ mL$$ of $$0.1\ M\ AgNO_{3}+50\ mL$$ of $$0.2\ M\ KI$$
  • $$100\ mL$$ of $$0.2\ M\ AgNO_{3}+100\ mL$$ of $$0.1\ M\ KI$$
  • $$100\ mL$$ of $$0.1\ M\ AgNO_{3}+100\ mL$$ of $$0.15\ M\ KI$$
Which of the following statement is not true about the oil-in-water type emulsion ?
  • Addition of small amount of water, no separate layer of water is formed
  • Addition of a small amount of oil soluble dye renders the entire emulsion coloured
  • Addition of oil results in the formation of two layers
  • Addition of a small amount of an electrolyte increases the conductivity of the emulsion
Chromatography is based on :
  • Physical adsorption
  • Chemical adsorption
  • Hydrogen bond
  • Adsorption
Peptization involves:
  • precipitation of colloidal particles
  • disintegration of colloidal aggregates
  • purification of colloids
  • impact of molecules of the dispersion medium on the colloidal particles
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