At room temperature, the reaction between NO and O₂ to give NO₂ is fast while that of between CO and O₂ is slow. It is because

• the intrinsic energy of the reaction 2NO + O₂ $\rightleftharpoons$ 2NO₂ is less

• CO is smaller in size than that of NO

• CO is poisonous

• the activation energy for the reaction 2 NO + O₂ $\rightleftharpoons$ 2NO₂ is less

A radioactive isotope having a half-life of 3 days was received after 12 days. It was found that there were 3 g of the isotope in the container. Find the initial weight of the isotope, when it was packed (antilog 1.203 = 16)

• 12 gm

• 24 gm

• 36 gm

• 48 gm

Transition state 2 (TS2) is structurally most likely as a/an

• intermediate 2

• product

• intermediate 1

• transition state 3(TS3)

Which graph shows zero activation energy for reaction?

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

• t_1/2 ∝ a°

• t_1/2  ∝ a²

• t_1/2  ∝ a

• t_1/2  ∝ 1/a

During nuclear explosion one of the products is ⁹⁰Sr with half-life of 28.1 yr. If 1 μg of ⁹⁰Sr was absorbed in the bones of a newly born body instead of calcium, how much of it will remain after 60 yr, if it is not lost metabolically?

• 0.184 μg

• 0.025 μg

• 0.262 μg

• 0.228 μg

257.

The half-life period of a radioactive element is 30 days. After 90 days, which of the following quantity will be left?

• 1/2

• 1/6

• 1/8

• 1/4

In a first order reaction, the concentration of the reactant, decreases from 0.8 M to 0.4 M in 15 min. The time taken for the concentration to change from 0.1 M to 0.025 M is

• 30 min

• 15 min

• 7.5 min

• 160 min

In a reaction, A + B → C, the rate expression is R = k [A][B]². If the concentration of both the reactant is doubled at constant volume, then the rate of the reaction will be

• eight times

• double

• quadruple

• triple

Which graph represents the zero order reaction [A (g) → B (g)]