General
✓✗The reaction A → B follows first order kinetics. The time taken for 0.8 mol of A to produce 0.6 mol of B is 1 hour. What is the time taken for conversion of 0.9 mol of A to produce 0.675 mol of B?
- 0.5 hour
- 0.25 hour
- 1 hour
- 2 hours
General
✓✗A first order reaction has t1/2 = 300 s at 300 K and t1/2 = 150 s at 320 K. The activation energy is (log 2 = 0.301) (R = 8.314 J K−1 mol−1)
- 55.3 kJ mol−1
- 27.7 kJ mol−1
- 0.3 kJ mol−1
- 12.0 kJ mol−1
General
✓✗Threshold energy is equal to
- activation energy − average energy of the reactants
- activation energy + average energy of the reactants
- enthalpy of reaction
- activation energy of the reverse reaction
General
✓✗Assertion: The half-life of a first order reaction is independent of the initial concentration.
Reason: For a first order reaction, t1/2 = 0.693/k.
Reason: For a first order reaction, t1/2 = 0.693/k.
- Both Assertion and Reason are true and Reason is the correct explanation of Assertion
- Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- Assertion is true but Reason is false
- Both Assertion and Reason are false
General
✓✗In the Arrhenius plots (ln k vs 1/T) of two reactions X and Y, the line for X is steeper. Hence
- Y has the higher activation energy
- X has the higher frequency factor
- X has the higher activation energy
- both have the same activation energy
General
✓✗For a zero order reaction, [A] falls from 0.8 M to 0.6 M in 20 min. The time taken for [A] to fall from 0.6 M to 0.2 M is
- 60 min
- 20 min
- 40 min
- 80 min
General
✓✗For the reaction BrO3− + 5Br− + 6H+ → 3Br2 + 3H2O, which of the following relations correctly represents the consumption of bromide ions and the formation of bromine?
- \( \dfrac{d[\mathrm{Br^-}]}{dt} = \dfrac{3}{5}\dfrac{d[\mathrm{Br_2}]}{dt} \)
- \( \dfrac{d[\mathrm{Br^-}]}{dt} = \dfrac{5}{3}\dfrac{d[\mathrm{Br_2}]}{dt} \)
- \( \dfrac{d[\mathrm{Br^-}]}{dt} = -\dfrac{5}{3}\dfrac{d[\mathrm{Br_2}]}{dt} \)
- \( \dfrac{d[\mathrm{Br^-}]}{dt} = -\dfrac{3}{5}\dfrac{d[\mathrm{Br_2}]}{dt} \)
General
✓✗In 10 s, the concentration of a reactant falls from 0.50 M to 0.30 M. The average rate of the reaction is
- 0.05 mol L−1 s−1
- 0.02 mol L−1 s−1
- 0.03 mol L−1 s−1
- 0.2 mol L−1 s−1
General
✓✗The temperature coefficient of a reaction is the ratio of rate constants at
- 298 K and 273 K
- 0 K and 298 K
- any two temperatures
- two temperatures differing by 10 °C (usually 308 K and 298 K)
General
✓✗The rate constant of a reaction is given by log k = 14.34 − 1.25 × 104 K/T. The activation energy is (R = 8.314 J K−1 mol−1)
- 239.3 kJ mol−1
- 119.7 kJ mol−1
- 28.8 kJ mol−1
- 103.9 kJ mol−1
General
✓✗Collisions that lead to the formation of products are called
- random collisions
- ineffective collisions
- effective collisions
- elastic collisions
General
✓✗The rate constant of a zero order reaction is 0.02 mol L−1 s−1. If [R]0 = 0.4 mol L−1, its half-life is
- 10 s
- 20 s
- 5 s
- 34.65 s
General
✓✗A first order reaction has a rate constant of 2.303 × 10−3 s−1. The time required for 40 g of this reactant to reduce to 10 g will be (Given: log10 2 = 0.3010)
- 230.3 s
- 2000 s
- 301 s
- 602 s
General
✓✗Assertion: A catalyst does not alter the equilibrium constant of a reaction.
Reason: A catalyst lowers the activation energies of the forward and backward reactions equally.
Reason: A catalyst lowers the activation energies of the forward and backward reactions equally.
- Both Assertion and Reason are true and Reason is the correct explanation of Assertion
- Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- Assertion is true but Reason is false
- Both Assertion and Reason are false
General
✓✗A zero order reaction has a half-life of 50 s when [A]0 = 0.5 M. Its half-life when [A]0 = 0.2 M is
- 50 s
- 20 s
- 10 s
- 125 s