The age of a specimen t is realted to the daughter/ parent ratio of number of atoms (D/ P) by the equation (λ = decay constant)

• t = $\frac{1}{\mathrm{\lambda }} \ln \left\{\frac{\mathrm{D}}{\mathrm{P}}\right\}$

• t = $\frac{1}{\mathrm{\lambda }} \ln \left\{1 + \frac{\mathrm{P}}{\mathrm{D}}\right\}$

• t = $\frac{1}{\mathrm{\lambda }} \ln \left\{2 + \frac{\mathrm{P}}{\mathrm{D}}\right\}$

• t = $\frac{1}{\mathrm{\lambda }} \ln \left\{1 + \frac{\mathrm{D}}{\mathrm{P}}\right\}$

Which one of the following set of units represents the smallest and largest amount of energy respectively?

• J and erg

• erg and cal

• cal and eV

• eV and lit-atom

For the reaction 2N₂O₅(g) → 4NO₂(g) + O₂(g) if he concentration of NO₂ increases by 5.2× 10^-3 M in 100 s then the rate of the reaction is 

• 1.3 × 10^-5 Ms^-1

• 0.5 × 10^-4 Ms^-1

• 7.6 × 10^-4 Ms^-1

• 2.5 × 10^-5 Ms^-1

A first order reaction is 10% complete in 20 min. The time taken for 19% completion is :

• 30 min

• 40 min

• 50 min

• 38 min

The data for the reaction A + B → C

The rate law corresponds to the above data is :

• rate = k [B]³

• rate = k [B]⁴

• rate = k[A] [B]³

• rate = k [A]² [B]²

A radioactive isotope has a half-life of 8 days. If today 125 mg is left over. What was its original weight 32 days earlier ?

• 6 g

• 5 g

• 4 g

• 2 g

The rate of a reaction is doubled for every 10° rise in temperature. The increase in reaction rate as a result of temperature rise from 10° to 100° is :

• 112

• 512

• 400

• 614

Which of the following statement is not correct?

• In zero order reaction the rate of the reaction remains constant throughout

• A second order reaction would become a pseudo first order reaction when one of the reactants is taken in large excess

• The value of first order rate constant expends on the units of the concentration terms used

• In a first order reaction the plot of log (a - x) vs time gives a straight line

The number of α and β particles emitted in the chain of reactions leading to the decay of ${}_{92}{}^{238}$U to ${}_{82}{}^{206}$Pb :

• 8 β particles and 6 α particles

• 5 α particles and O β particles

• 8 α and 6 β particles 

• 10 α particles and 10 β  particles

120.

The disintegration constant of radium with half-life 1600 yr is

• 2.12 × 10^-4 yr^-1

• 4.33 × 10^-4 yr^-1

• 3.26 × 10^-3 yr^-1

• 4.33 × 10^-12 yr^-1