CBSE Class 12 Chemistry – MCQ and Online Tests – Unit 4 – Chemical Kinetics
Every year CBSE conducts board exams for 12th standard. These exams are very competitive to all the students. So our website provides online tests for all the 12th subjects. These tests are also very effective and useful for those who preparing for competitive exams like NEET, JEE, CA etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
These online tests are based on latest CBSE Class 12 syllabus. While attempting these our students can identify the weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly.
CBSE Class 12 Chemistry – MCQ and Online Tests – Unit 4 – Chemical Kinetics
Question 1.
A reaction in which reactants (R) are converted into products (P) follows second order kinetics. If concentration of R is increased by four times, what will be the increase in the rate of formation of P?
(a) 9 times
(b) 4 times
(c) 16 times
(d) 8 times
Answer
Answer: (c) 16 times
Question 2.
Which of the following, is an example of a fractional order reaction?
(a) NH4NO2 → N2 + 2H2O
(b) NO + O3 → NO2 + O2
(c) 2NO + Br2 → 2NOBr
(d) CH3CHO → CH4 + CO
Answer
Answer: (d) CH3CHO → CH4 + CO
Question 3.
The order of reaction is decided by
(a) temperature
(b) mechanism of reaction as well as relative concentration of reactants
(c) molecularity
(d) pressure
Answer
Answer: (b) mechanism of reaction as well as relative concentration of reactants
Question 4.
The unit of rate constant for the reaction
2H2 + 2NO → 2H2O + N2
which has rate = K|H2||NO|², is
(a) mol L-1 s-1
(b) s-1
(c) mol-2 L² s-1
(d)mol L-1
Answer
Answer: (c) mol-2 L² s-1
Question 5.
For a reaction nx – y → z the rate of reaction becomes twenty seven times when the concentration of X is increased three times. What is the order of the reaction?
(a) 2
(b) 1
(c) 3
(d) 0
Answer
Answer: (c) 3
Question 6.
The unit of rate and rate constant are same fora
(a) zero order reaction
(b) first order reaction
(c) second order reaction
(d) third order reaction
Answer
Answer: (a) zero order reaction
Question 7.
The decomposition of dimethyl ether is a fractional order reaction. The rate is given by rate =k(PCH3OCH3)3/2. If the pressure is measured in bar and time in minutes, then what are the units of rate and rate constant?
(a) bar min-1, bar2 min-1
(b) bar min-1, bar1/2 min-1
(c) bar1/2 min-1, bar2 min-1
(d) bar min-1, bar1/2 min-1
Answer
Answer: (b) bar min-1, bar1/2 min-1
Question 8.
Fora reaction x + y → z, rate ∝ |X|. What is (i) moleculariiy and (ii) order of reaction?
(a) (i)2, (ii) 1
(b) (i)2,(ii) 2
(c) (i) 1, (ii) 1
(d) (i) 1, (ii) 2
Answer
Answer: (a) (i)2, (ii) 1
Question 9.
Fora unimolecular reaction
(a) the order and molecuiarity of the slowest step are equal to one
(b) molecuiarity of the reaction can be zero, one or two
(c) molecuiarity of the reaction can be determined only experimentally
(d) more than one reacting species are involved in one step
Answer
Answer: (a) the order and molecuiarity of the slowest step are equal to one
Question 10.
The rate constant of a reaction depends upon
(a) temperature of the reaction
(b) extent of the reaction
(c) initial concentration of the reactants
(d) the time of completion of reaction
Answer
Answer: (d) the time of completion of reaction
Question 11.
If the rate of a reaction is expressed by, rate = A [A]² [B], the order of reaction will be
(a) 2
(b) 3
(c) 1
(d) 0
Answer
Answer: (b) 3
Question 12.
The chemical reaction, 2O3 → 3O2 proceeds as
O3 \(\rightleftharpoons\) O2 + |O| (fast)
|O| + O3 → 2O2 (slow)
The rate law expression will be
(a) Rate = k [O] [O3]
(b) Rate = k [O3]² [O2]-1
(c) Rate = k [O3]²
(d) Rate = k [O2] [O]
Answer
Answer: (b) Rate = k [O3]² [O2]-1
Question 13.
The number of molecules of the reactants taking part in a single step of the reaction is indicative of
(a) order of a reaction
(b) molecuiarity of a reaction
(c) fast step of the mechanism of a reaction
(d) half-life of the reaction
Answer
Answer: (b) molecuiarity of a reaction
Question 14.
The overall rate of a reaction is governed by
(a) the rate of fastest intermediate’step
(b) the sum total of the rates of all intermediate steps
(c) the average of the rates of all the intermediate steps
(d) the rate of slowest intermediate step
Answer
Answer: (d) the rate of slowest intermediate step
Question 15.
In chemical equation H2 (g) + I2 (g) \(\rightleftharpoons\) 2HI (g) the equilibrium constant Kp depends on
(a) total pressure
(b) catalyst used
(c) amount of H2 and I2
(d) temperature
Answer
Answer: (b) catalyst used
Question 16.
Rate constant in case of first order reaction is
(a) inversely proportional to the concentration units
(b) independent of concentration units
(c) directly proportional to concentration units
(d) inversely proportional to the square of concentration units
Answer
Answer: (b) independent of concentration units
Question 17.
In pseudo unimolecular reactions
(a) both the reactants are present in low concentration
(b) both the reactants are present in same concentration
(c) one of the reactant is present in excess
(d) one of the reactant is non-reactive
Answer
Answer: (c) one of the reactant is present in excess
Question 18.
A first order reaction takes 40 min for 30% decomposition. What will be t12?
(a) 77.7 min
(b) 52.5 min
(c) 46.2 min
(d) 22.7 min
Answer
Answer: (a) 77.7 min
Question 19.
Half life period of a first order reaction is 10 min. What percentage of the reaction will be completed in 100 min?
(a) 25%
(b) 50%
(c) 99.9%
(d) 75%
Answer
Answer: (c) 99.9%
Question 20.
The activation energy in a chemical reaction is defined as
(a) the difference in energies of reactants and products
(b) the sum of energies of reactants and products
(c) the difference in energy of intermediate complex with the average energy of reactants and products
(d) the difference in energy of intermediate complex and the average energy of reactants
Answer
Answer: (d) the difference in energy of intermediate complex and the average energy of reactants
Question 21.
A first order reaction has a rate constant 1.15 × 10-3s-1. How long time will 5 g of this reactant take to reduce to 3 g?
(a) 444 s
(b) 400 s
(c) 528 s
(d) 669 s
Answer
Answer: (a) 444 s
Question 22.
Radioactive disintegration is an example of
(a) zero order reaction
(b) first order reaction
(c) second order reaction
(d) third order reaction
Answer
Answer: (b) first order reaction
Question 23.
A plot of log (a – x) against time t is a straight line. This indicates that the reaction is of
(a) zero order
(b) first order
(c) second order
(d) third order
Answer
Answer: (b) first order
Question 24.
In a reaction, 2X → Y, the concentration of X decreases from 0.50 M to 0.38 M in 10 min. What is the rate of reaction in Ms-1 during this interval ?
(a) 2 × 10-4
(b) 4 × 10-2
(c) 2 × 10-2
(d) 1 × 10-2
Answer
Answer: (a) 2 × 10-4
Question 25.
Rate of which reaction increases with temperature?
(a) Exothermic reaction
(b) Endothermic reaction
(c) (a) and (b) both
(d) None of the above
Answer
Answer: (c) (a) and (b) both
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