The half life of a radioactive element is 40 days. Calculate the average life

• 5.76 days

• 57.6 days

• 646 days

• 4.56 days

332.

There is a steam of neutrons with a kinetic energy of 0.0327 eV. If the half life of neutrons s 700 s, what fraction of neutrons will decay before they travel a distance of 10 km?

• 0.001

• 0.004

• 0.006

• 0.009

One of the hazardous explosion is the generation of ⁹⁰Sr and its subsequent incorporation in bones. This nuclide has a half life of 28.1 years. Suppose one microgram was absorbed by a new born child. How much ⁹⁰Sr will remain in his bones after 20 years?

• 0.061 µg

• 0.080µg

• 0.050µg

• 0.030µg

For a reaction, the half-life is independent of initial concentration. What is the order of that reaction?

• Zero

• One

• Two

• Three

The rate of reaction , 2NO + Cl₂ $\rightleftharpoons$ 2NOCl becomes double when the concentration of Cl₂ is doubled. However, when the concentration of both the reactants is doubled the rate becomes eight times. What is order of the reaction?

• First

• Second

• Third

• Zero

How will the rate of reaction , 2NO + O₂ $\to$ 2NO₂ change, if the volume of the reaction vessel is doubled?

• It will diminish to 1/4 of the initial value

• It will diminish to 1/8 of the initial value

• It will grow four times

• It will grow eight times

For a chemical reaction A $\to$ B, the rate of the reaction is 2x10^-3 mol dm^-3 s^-1 , when the initial concentration is 0.05 mol dm^-3 . The rate of the same reaction is 1.6 x 10^-2 mol dm^-3 s^-1 , when the initial concentration is 0.1 mol dm^-3 .The order of the reaction is :

• 2

• 0

• 3

• 1

Consider the following statements :
I. Increase in concentration of reactant increases the rate of a zero order reaction
II. Rate constant k is equal to collision frequency A , if E_a =0

III. Rate constant k is equal to collision
frequency A , if E_a = ∞
IV. ln k vs T is a straight line
V. ln k vs 1/T is a straight line

Correct statements are :

• I and IV

• II and V

• III and IV

• II and III

The chemical reaction, 2O₃ $\to$ 3O₂ proceeds as follows:

Step 1 : O₃ $\rightleftharpoons$ O₂ + O  ...(fast)

Step 2 : O + O₃ $\to$2O₂ ...(slow)

The rate law expression should be

• r = k' [O₃][O₂]

• r = k'[O₃]²[O₂]^-1

• r = k'[O₃]²

• unpredictable

A first order reaction, which is 30% complete in 30 minutes has a half-life period of

• 102.2 min

• 58.2 min

• 24.2 min

• 120.2 min