The t_0.5 of a radioactive isotope is 1.5 h .How long will it take for its activity to be reduced to $\frac{1}{16}$  of its original value ?

• 3.0 h

• 360 min

• 4.5 h

• 600 min

Assertion : The overall order of the reaction is the sum of the exponents of all the reactants in the rate expression.

Reason : There are many higher order reactions.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

The concentration of a reactant X decreases from 0.1 M to 0.005 Min 40 min .If the reaction follows first order kinetics , the rate of the reaction when the concentration of X is 0.01 M will be :

• 1.73 x 10^-4 M min^-1

• 3.47 x 10^-4 M min^-1

• 3.47 x 10^-5 M min^-1

• 7.5 x 10^-4 M min^-1

674.

For the reaction, 2NO₂ + F₂ $\to$2NO₂F,  following mechanism has been provided.

${\mathrm{NO}}_{2 }+ {\mathrm{F}}_2 \stackrel{\mathrm{slow}}{\to } {\mathrm{NO}}_2\mathrm{F} + \mathrm{F}$

${\mathrm{NO}}_{2 } + \mathrm{F} \stackrel{ \mathrm{fast}}{\to }{\mathrm{NO}}_2\mathrm{F}$

Thus, rate expression of the above reaction can be written as

• r= k [NO₂]₂[F₂]

• r = k [NO₂][F₂]

• r = k [NO₂]

• r = k [F₂]

For a reaction A + B $\to$ C + D if the concentration of A is doubled without alterning the concentration of B , the rate gets doubled . If the concentration of B is increased by nine times without alterning the concentration of A , the rate gets tripled .The order of the reaction is :

• 2

• 1

• 3/2

• 4/3

What is the half-life of ₆C¹⁴ , if its disintegration constant is 2.31 x 10^-4 yr^-1 ?

• 0.3 x 10⁴ yr

• 0.3 x 10³ yr

• 0.3 x 10⁸ yr

• 0.3 x 10² yr

In a homogenous reaction, A $\to$ B + C + D the initial pressure was P₀ and after time t it was P. Expression for rate constant k in terms of P₀, P and t will be

• $k = \frac{2.303}{t}\log \frac{2P_0}{3P_0 - P}$

• $k = \frac{2.303}{t}log\frac{2P_0}{P_0 - P}$

• $k = \frac{2.303}{t}\log \frac{3P_0 - P}{2P_0}$

• $k = \frac{2.303}{t}\log \frac{2P_0}{3P_0 - 2P}$

Which curve corresponds to the temperature dependence of the rate R of a simple one step reaction?

Acid hydrolysis of sucrose is a

• pseudo first order reaction

• zero order reaction

• second order reaction

• unimolecular reaction.

Assertion : In rate law, unlike in the expression for equilibrium constants, the exponents for concentrations do not necessarily match the stoichiometric coefficients.

Reason : It is the mechanism and not the balanced chemical equation for the overall change that governs the reaction rate.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false