After how many seconds will the concentration of the reactant in

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 Multiple Choice QuestionsMultiple Choice Questions

71.

For a first order reaction, the half-life period is

  • dependent on the square of the initial concentration

  • dependent on first power of initial concentration

  • dependent on the square root of initial concentration

  • independent on initial concentration


72.

A radioactive isotope having t1/2 = 3 days was read after 12 days. If 3g of isotope is contained in container, the initial weight of isotope was

  • 12g

  • 24g

  • 36g

  • 48g


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73.

After how many seconds will the concentration of the reactant in a first order reaction be halved if the rate constant is 1.155 x 10-3 s-1?

  • 600

  • 100

  • 60

  • 10


A.

600

Rate constant k = 1.155 x 10-3 s-1

k =2.303t log a(a-x)   a= a, (a-x) =a2t1/2 = 2.303t log aa/2        =2.3031.155 × 10-3 log 2       =2.3031.155 × 10-3× 0.3010      = 0.693 × 1031.155t1/2= 0.693t=0.6931.155 × 10-3       = 600 s


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74.

For a reaction,  A + 2B  C, rate is given by +d[C]dt= k [A] [B],hence, the order of the reaction is

  • 3

  • 2

  • 1

  • 0


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75.

In a multistep reaction, the overall rate of reaction is equal to the

  • rate of slowest step

  • rate of fastest step

  • average rate of various step

  • the rate of last step


76.

The first order integrated rate equation is

  • k = xt

  • k = 2.303t logaa - x

  • k = 1t  ln aa - x

  • k = 1txa(a - x)


77.

For nuclear fusion reactions, the fusion temperature is of the order of

  • 105 K

  • 103 K

  • 107 K

  • 100 K


78.

Unit of decay constant of radioactive disintegration is

  • time

  • min-2

  • time-1

  • time mol-1


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79.

A first order reaction is given as A  products. Its integrated equation is

  • k = 2.303tlog  a-xa

  • k = 1t log aa-x

  • k = 2.303t log aa-x

  • -k = 1t log a -xa


80.

The units of rate constant for first order reaction are

  • mol L-1s-1

  • s-1

  • Lmol-1s-1

  • L2mol-2s-1


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