Eleventh Chapter Solved Exercise MCQs Of FSc First Year Chemistry

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First chapter solved MCQs with explanation

1: In zero order reaction, the rate is independent of

  1. Temperature of reaction
  2. Concentration of reactants
  3. Concentration of products
  4. None of these

Explanation

In zero order reaction reactions the rate of reaction do not depend upon the concentration of reactants. So the option b is the correct answer.

2: If the rate of reaction for 2A + B –> products is k [A]2 [B] and A is present in large excess then order of reaction is

  1. 1
  2. 2
  3. 3
  4. None of these

Explanation

The rate expression of the reaction is

2A + B –> Products

The substance which is taken in large excess does not control the rate of reaction of a chemical reaction.

SO the rate will only depend upon concentration of substance B. The exponent of substance B in the rate expression is unity. Hence the reaction is 1st order, when A is taken in large excess. Therefore, option a is the correct answer.

3: The rate of reaction

  1. Increases as the reaction proceeds
  2. Decreases as the reaction proceeds
  3. Remains the same as the reaction proceeds
  4. May decrease or increase as the reaction proceeds

Explanation

According to the law of mass action the rate of reaction depends upon the concentration of reactants. As the reaction proceeds, the concentration of reactants fall down consequently, the rate of reaction drops every moment.

So option b is correct.

4: With increase in 100C temperature the rate of reaction doubles. This increase in rate of reaction is due to

  1. Decrease in activation energy of reaction
  2. Decrease in the number of collisions between reactant molecules
  3. Increase in activation energy of reactants
  4. Increase in number of effective collisions

Explanation

When the temperature of reaction is increased the total number of collisions happening in the molecules increase. Hence the effective collisions also increase. For 100C rise of temperature rate of reaction is almost doubled. Therefore, option d is the correct answer.

5: The unit of the rate constant in same as that of the rate of reaction in

  1. First order reaction
  2. Second order reaction
  3. Zero order reaction
  4. Third order reaction

Explanation

For zero order reaction

Rate= k x [reactants]0

Rate= k x 1

Rate=K

Hence the units of rate and rate constant are same for zero order reaction. Therefore, option c is the correct answer.