ECAT Pre Engineering Chemistry Chapter 11 MCQ Test With Answer

If the rate of decay of radioactive isotope decreases from 200 cpm to 25 cpm after 24 hours, what is its half life :

• 8 hours A
• 6 hours B
• 4 hours C
• 3 hours D

The unit rate of constan K ismole^-1 dm³S^-1for a chemical reaction, the order of reaction is :

• 3 A
• 2 B
• 1 C
• 0 D

A pseudo uni-molecular reaction has order of reaction :

• 3 A
• 2 B
• 1 C
• 0 D

A catalyst is a substance which increase the rate of a chemical reaction, but remains unchanged at the end of reaction, nut remains unchanged at the end of reaction, because

• It increases the temperature A
• It increase the surface area B
• It increases the rate constant C
• It decrease the energy energy of activation D

• Rate = k[FeCl₃] [Kl]² A
• Rate = k[Fe⁺³][Cl^-1] [Kl] B
• Rate = k[Fe⁺³] [Cl^-1][K;] C
• Rate = k[Kl]³[FeCl₃]° D

If a reactant or product of a reaction absorbs radiation, then physical method for determining the rate of reaction is

• Spectrometry A
• Refractometry B
• Conductivity measurement C
• Optical method D

The rate constant k of a reaction activation energy Ea and temperature are related by Arrhenius in the form of an equation which is

• 
  A
• 
  B
• 
  C
• 
  D

It rate law of an equation is written asdx/dt=K[A][B] ?

• Reaction is independent of the concentration of A and B. A
• Product is decreasing with passage of time. B
• Reactant in increasing with passage of time. C
• Reactant is increasing with passage of time. D

• First order A
• Pseudo first order B
• Second order C
• Zero order D

With increases of 10°C temperature the rate of reactiondoubles. This increase in rate of reactionis due to :

• Decrease in activation energy or reaction. A
• Decrease in number of collisions between reactant molecules. B
• Increase in activation energy of reactants. C
• Increase in number of effective collisions D

• Initial concentration of reaction A
• Initial concentration of products B
• Final concentration of products C
• Order of the reaction D

It is common observation that rates of chemical reactions differ :

• Greatly. A
• A little bit. B
• Moderately. C

By the use of catalysis the energy of activation is

• Decreased A
• Increased B
• Not affected C
• None D

Complex protein molecules which catalyses the organic reactions in the living cells are called

• Living organisms A
• Enzymes B
• Viruses C
• Bacteria D

• Rate is independent of concentration of water since it is in excess A
• Rate is independent of concentration of ester since it is in exces B
• Rate depends upon the concentration of acid catalyst added C
• Rate = k[CH₃COOC₂H₅]^1/2[H₂O]^1/2 D

When copper is allowed to react with HNO₃, the reaction is slow in the beginning, finally becomes very fast. It is due to the formation of an auto catalyst which is

• Cu(NO₃)₂ A
• CuO B
• O₂ C
• HNO₂ D

Optical rotation method is sued when

• Reaction involve ions A
• Change of refractive indices B
• Reactions involving change of optical activity C
• None of the above D

Factor which slows down the rate of reaction is

• Small size of the particles of the reactant A
• High temperature of reaction B
• More concentration of reactant C
• Lowering the temperature D

The rate of reaction :

• Increase as the reaction proceeds. A
• Decreases as the reaction proceeds. B
• Remains the same as the reaction proceed. C
• May decrease or increase as the reaction proceeds. D

The rate of reaction determined at a given time is called

• Average rate A
• Instantaneous rate B
• Specific rate C
• Overall rate D

The unit of rate of reaction is

• mole dm^-3 A
• mole Kg^-1 B
• moles dm^-3sec^-1 C
• grams dm^-3 D

The rate of reaction b/w two specific time intervals is called :

• Instantaneous rate of reaction. A
• Average rate of reaction. B
• Rate of a reaction. C
• Minimum rate of a reaction. D

The unit of rate constant k is the same as that of the rate of reaction in

• First order reaction A
• Second order reaction B
• Third order reaction C
• Zero order reaction D

A substance which increases the rate of a reaction without being consumed during the reaction is called

• An autocatalyst A
• A catalyst B
• A negative catalyst C
• All of these D

When the rate of reaction is entirely independent of the conc. of reaction molecules then order of reaction is

• Zero A
• First B
• Second C
• Third D

• Small change in concentration of product A
• Small time internal B
• Co-efficient of the reactant C
• Co-efficient of the product D

Which of the following reactions occur at moderate rate :

• Rusting of iron A
• Chemical weathering of stone work of buildings by acidic gases in atmosphere. B
• Hydrolysis of an ester C
• Fermentation of sugars D

With increases in temperature of 10 K of the reacting gases the rate of reaction is doubled because

• Increase in number of collisions A
• Number of molecules having energy more than Ea is doubled B
• Increase in order of reaction C
• Increase in surface area D

In exothermic reaction decrease in potential energy of the products will result in

• Decreases in kinetic energy of the particles A
• Increases in kinetic energy of the particles B
• No change in kinetic energy C
• Decreases in activation energy D

In the reaction of oxalic acid with KMnO₄and H₂SO₄is slow at the beginning but after sometimes the reaction becomes faster due to

• Formation of MnSO₄which acts as 'Auto catalyst A
• Formation of CO₂which acts as 'Auto catalyst B
• Formation of K₂SO₄which acts as 'Auto catalyst C
• Evolution of O₂gas which acts as 'Auto catalyst D