# Important Questions for Class 12 Chapter 4 - Chemical Kinetics

Important questions based on NCERT syllabus for Chapter 4 - Chemical Kinetics:

Question-1: The conversion of molecules X to Y follows second order kinetics. If concentration of X is increased to three times how will it affect the rate of formation of Y ?

Solution: The reaction is : X—>Y
According to rate law,
rate = k[X]2
If [X] is increased to 3 times, then the new rate is
rate’ = k[3X]2
rate’ = 9 k [X]2 = 9 rate
Thus, rate of reaction becomes 9 times and hence rate of formation of Y increases 9-times.

Question-2: What will be the effect of temperature on rate constant?

Solution: With the rise in temperature by 10°, the rate constant of a reaction is nearly doubled. The dependence of rate constant on temperature is given the Arrhenius equation, k = A e-Ea/RT where A is the Arrhenius constant and Ea is activation energy of the reaction.

Question-3: Mention the factors that affect the rate of a chemical reaction.

Solution: Factors affecting the rate 6f chemical reaction are following:
(i) Natpre of reactants
(ii) Concentration of reactants
(iii) Surface area of reactants
(iv) Effect of temperature
(v) Presence of catalyst
(vi) Presence of light