CBSE Questions for Class 12 Engineering Chemistry Surface Chemistry Quiz 4 - MCQExams.com

Which of the following catalyst is used in contact process for manufacture of $$H_{2}SO_{4}$$?
  • Oxides of nitrogen
  • $$V_{2}O_{5}$$
  • $$Fe_{2}O_{3}$$
  • Platinised asbestos

Gelatin protects
  • Gold sol
  • $$\mathrm{A}\mathrm{s}_{2}\mathrm{S}_{3}$$ sol
  • $$\mathrm{F}\mathrm{e}(\mathrm{O}\mathrm{H})_{3}$$ sol
  • All of these
The process of making colloidal solution from a precipitate is called ________.
  • coagulation
  • vulcanization
  • peptization
  • flocculation
In presence of acetanilide, the rate of decomposition of $$H_{2}O_{2}$$ reduced. Acetanilide is called a positive catalyst.
  • True
  • False
Which of the following statement is incorrect?
  • Enzymes are in colloidal state
  • Enzymes are catalysts
  • Enzymes can catalyze any reaction
  • Urease is an enzyme
Finely powered or colloidal catalyst particles having small surface area are rich in free valencies.
State whether the statement is True or False
  • The statement is True 
  • The statement is False
  • Neither
  • Finely powered or colloidal catalyst particles having large surface area are rich in free valencies.
Which of the following statements about a catalyst is/are true?
  • A catalyst accelerates the reaction by bringing down the energy of activation.
  • A catalyst does not take part in the reaction.
  • A catalyst makes the reaction more feasible by making the $$\Delta G^{\circ}$$ more negative.
  • A catalyst makes the equilibrium constant of the reaction more favourable for the forward reaction.
The magnitude of ______________ decreases in the presence of a catalyst.
  • activation energy
  • dissociation energy
  • energy barrier
  • intermolecular forces
Which one of the following is an example of homogeneous catalysis?
  • Haber's process of synthesis of ammonia
  • Catalytic conversion of $$SO_{2}$$ to $$SO_{3}$$ in Contact process
  • Catalytic hydrogenation of oils
  • Acid hydrolysis of methyl acetate
In a reversible reaction, a catalyst :
  • increases the rate of the forward reaction only
  • increases the rate of forward reaction to a greater extent then that of the backward reaction
  • increases the rate of the forward reaction and decreases that of the backward reaction to different extent
  • increases the rate of the forward and backward reaction equally
Catalytic poisoning is due to:
  • increasing activation energy
  • adsorption of poisoner on the reactants surface
  • adsorption of poisoners on the catalyst surface
  • increase in heat of reaction
Which is not correct for an oil-water emulsion?
  • It imparts dye colour with water soluble dye.
  • It can be diluted with water.
  • It has higher viscosity in comparison to water-oil emulsion.
  • It consists of vanishing cream.
Which one of the following characteristics is not correct for physical adsorption?
  • Adsorption is spontaneous
  • Both enthalpy and entropy of adsorption
  • Adsorption on solid is reversible
  • Adsorption increases with increase in temperature
Which reactions represents heterogeneous catalysis?
  • Decomposition of KClO$$_3$$ in presence of MnO$$_2$$
  • Ostwald process for HNO$$_3$$
  • Contact process for H$$_2$$SO$$_4$$
  • Acidic hydrolysis of ester
Bredig's arc method involves :
  • dispersion
  • condensation
  • peptization
  • dispersion and condensation both
A catalyst is a substance that :
  • helps in attaining equilibrium faster (if any)
  • increases the rate of forward and backward reaction (if any)
  • lowers the threshold energy level
  • provides new pathway to reaction
About positive and negative catalyst, which of the following statements is incorrect?
  • Positive catalyst lowers the energy of activation
  • Negative catalyst decreases the energy of activation
  • Positive catalyst increases the rate of reaction
  • Negative catalyst functions to remove active intermediates
$$CO + H_2{\rightarrow } CH_3 OH$$ 

Which catalyst is used in the above reaction?
  • $$MnO_2$$
  • $$FeCl_3$$
  • $$PdCl_2$$
  • $$ZnO/CuO$$
Which of the following is not an example of a heterogeneous catalysis?
  • Formation of $$SO_3$$ In the chamber process.
  • Formation of $$SO_3$$ in the contact process.
  • Hydrolysis of an ester in the presence of $$H^+$$ ions.
  • Combination of $$H_2$$ and $$Cl_2$$ in the presence of moisture.
Mark the incorrect statement. 
A catalyst :
  • remains chemically unchanged at the end of a chemical reaction
  • is used up in the course of a reaction
  • is a reactant required in small quantity
  • is not specific
What type of bond would exist between this soap and oil?
123680_22aa278538164f3f8fd7b0314448707c.png
  • Hydrogen bonds
  • Dispersion forces
  • Covalent bonds
  • Dipole-dipole forces
Which type of metals form effective catalysts?
  • Alkali metals
  • Transition metals
  • Alkaline earth metals
  • Radioactive metals
When oil and water are into the same vessel, two layers are observed with the less dense oil on top. These two liquids are said to be:
  • hydrophilic
  • hydrophobic
  • insoluble
  • immiscible
Which gas will be adsorbed on a solid to greater extent?
  • A gas having non polar molecule.
  • A gas having highest critical temperature $$\displaystyle \left ( T_{c} \right )$$.
  • A gas having lowest critical temperature.
  • A gas having highest critical pressure.
Cod liver oil is:
  • fat dispersed in water
  • water dispersed in fat
  • water dispersed in oil
  • fat dispersed in fat
Adsorption is multilayer in case of:
  • physical adsorption
  • chemisorption
  • in both
  • none of the these
Blood contains:
  • positively charged particles
  • negatively charged particles
  • neutral particles
  • negatively as well as positively charged particles
Catalytic poisoners act by:
  • coagulating the catalyst
  • getting adsorbed on the active centres on the surface of catalyst
  • chemical combination with any one of the reactants
  • none of the above
Select the correct statement(s).
  • When $$T\longrightarrow \infty$$ or $${{E}_{a}}\longrightarrow 0$$, then $$k=A$$.
  • A positive catalyst can change $$\Delta H$$ of the reaction.
  • A mixture of reactants may be thermodynamically unstable but kinetically stable.
  • A negative catalyst increases the activation energy of the reaction.
Reversible adsorption is:
  • chemical adsorption
  • physical adsorption
  • both
  • none
An emulsion is a colloidal system of ____________:
  • two solids
  • two liquids
  • one gas and one solid
  • one gas and one liquid
Cleansing action of soap occurs because:
  • oil and grease can be absorbed into the hydrophobic centres of soap micelles and washed away
  • oil and grease can be absorbed into hydrophilic centres of soap micelles and washed away
  • oil and grease can be absorbed into both hydrophilic and hydrophobic centres but cannot be washed away
  • cleansing action is not related to micelles
The catalyst used in making $$H_2SO_4$$ in contact process is :
  • $$V_2O_5$$
  • $$Fe_2O_3$$
  • $$Cr_2O_3$$
  • $$CrO_3$$
Which of the following element is responsible for oxidation of water to $$O_2$$ is biological processes?
  • Fe
  • Cu
  • Mn
  • Mo
Mention catalyst in the following reaction:

$$C_2H_4 {\rightarrow } CH_3 CHO$$  
  • $$MnO_2$$
  • $$FeCl_3$$
  • $$PdCl_2$$
  • $$ZnO/CuO$$
Adsorption is a surface phenomenon.
  • True
  • False
Which is not correct in case of catalyst?
  • A catalyst is active only in solution.
  • The addition of catalyst changes the equilibrium constant.
  • A catalyst speeds up forward reaction and slows the backward reaction.
  • The composition of equilibrium mixtures is not changed by a catalyst.
Which statements is true in case of catalyst?
  • The catalyst is unchanged chemically at the end of a reaction.
  • The catalyst accelerated the reaction.
  • In a reversible reaction, the catalyst alters the equilibrium position.
  • A small amount of catalyst is often sufficient to bring about a large change in reaction.
Thermal decomposition of $$KClO_3(s)$$ in presence of $$MnO_2(s)$$ is homogeneous catalysis.
  • True
  • False
Combination of $$N_2$$ and $$H_2$$ in presence of $$Fe$$ as catalyst is an example of homogeneous catalysis.
  • True
  • False
Which is true in case of catalyst?
  • A catalyst always initiate a reaction
  • A catalyst does not alter the position of equilibrium in a reversible reaction
  • A catalyst remains unchanged in quality and composition at the end of the reaction
  • Catalysts are sometimes very specific in respect of a reaction
Decomposition of $$H_2O_2$$ is prevented in presence of :
  • acetanilide
  • glycol
  • oxygen
  • none of the above
On adding few drops of dilute $$HCl$$ or $$FeCl_3$$ to freshly precipitated ferric hydroxide, a red coloured colloidal solution is obtained. This phenomenon is known as :
  • peptization
  • dialysis
  • protection
  • dissolution
Peptization is a process of :
  • precipitating colloidal particles.
  • purifying colloidal particles.
  • dispersing the precipitate into colloidal state.
  • none of the above.
Tanning of leather is the :
  • colouring of leather by chemicals
  • drying process to make the leather hard
  • polishing of leather to make it look attractive
  • coagulative hardening of the leather by chemicals
Gelatin is often used as an ingredient in the manufacture of ice-cream. The reason for this is :
  • to prevent the formation of a colloid.
  • to stabilize the colloid and prevent crystal growth.
  • to cause the mixture to solidify.
  • to improve the flavour.
The rate of decomposition of aldehyde $$(CH_3CHO)$$ into $$CH_4$$ and $$CO$$ in presence of $$I_2$$ at 800 K follows the rate law: $$r=K[CH_3CHO][I_2]$$. The decomposition is believed to go to the two step mechanism:

$$CH_3CHO+I_2\rightarrow CH_3I+HI+CO$$

$$CH_3I+HI\rightarrow CH_4+I_2$$

What is the catalyst for the reaction? Which of the two steps is the slower one?
  • $$HI, I^{st} \ step$$
  • $$I_2, I^{st} \ step$$
  • $$HI, II^{st}\  step$$
  • $$I_2, II^{st}\ step$$
Which of the following are governed by emulsion formation?
  • Preparation of food stuffs.
  • Food digestion in intestine.
  • Preparation of many cosmetic products.
  • Process of cementation.
The colloidal system in which the disperse phase and dispersion medium are both liquids is known as:
  • an emulsion
  • an aerosol
  • a gel
  • a foam
Rate of reaction (r) is plotted against temperature (T) for an enzyme catalysed reaction. Which of the following is correct representation?
0:0:1


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