In a first order reaction, the concentration of the reactant decr

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 Multiple Choice QuestionsMultiple Choice Questions

431.

Observe the following reaction 2A + B → C. The rate of formation of C is 2.2 × 10-3 mol L-1min-1. What is the value of - d[A]dt (in mol L-1min-1)?

  • 2.2 × 10-3 

  • 1.1 × 10-3 

  • 4.4 × 10-3 

  • 5.5  × 10-3 


432.

The rate constant of a first order reaction at 27°C is 10-3 min-1. The temperature coefficient of this reaction is 2. What is the rate constant (in min-1 ) at 17°C for this reaction ?

  • 10-3

  • 5 × 10-4

  • 2 × 10-3

  • 10-2


433.

What is the temperature at which the kinetic energy of 0.3 moles of helium is equal to the kinetic energy of 0.4 moles of argon at 400 K?

  • 400 K

  • 873 K

  • 533 K

  • 300 K


434.

What is the slope of the straight line for the graph drawn between ln k and 1/T, where k is the rate constant of a reaction at temperature T?

  • -Ea/ 2.303R

  • -Ea/R

  • Ea/R

  • R/Ea


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435.

Electrons with a kinetic energy of 6.023 × 104 J/mol are evolved from the surface of a metal, when it is exposed to radiation of wavelength of 600 nm. The minimum amount of energy required to remove an electron from the metal atom is

  • 2.3125 × 10-19 J

  • 3 × 10-19 J

  • 6.02 × 10-19 J

  • 6.62 × 10-34 J


436.

For a first order reaction at 27°C, the ratio of time required for 75% completion to 25% completion of reaction is

  • 3.0

  • 2.303

  • 4.8

  • 0.477


437.

At T (K), the ratio of kinetic energies of 4g of H2 (g) and 8 g of O2 (g) is

  • 1 : 4

  • 4 : 1

  • 2 : 1

  • 8 : 1


438.

Which one of the following plots is correct for a first order reaction?


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439.

Which one ofthe following statements is correct for the reaction?

CH3COOC2H5(aq) + NaOH(aq) → CH3COONa (aq) + C2H5OH (aq)

  • Order is two but molecularity is one

  • Order is one but molecularity is two

  • Order is one but molecularity is one

  • Order is two but molecularity is two


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440.

In a first order reaction, the concentration of the reactant decrease from 0.6 M to 0.3 M in 15 min. The time taken for the concentration to change from 0.1 M to 0.025 M in minutes is

  • 14

  • 12

  • 30

  • 3


C.

30

Since, concentration of the reactant decreases from 0.6 M to  0.3 M (i.e , halved) in 15 minutes, therefore half time for this reaction be 15 min

i.e, t1/2= 15min

Now for a first order reaction

k=0.693t1/2= 0.69315 min-1again,k= 2.303tlogA[A]0.69315=2.303tlog0.10.025t=2.303 × 150.693 log 4=2.303 × 150.693× 0.6020 = 30min


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