A hydrogenation reaction is carried out at 500 K. If the same reaction is carried out in the presence of a catalyst at the same rate, the temperature required is 400 K. If the catalyst lowers the activation barrier by 40 kJ mol^-1 the activation energy of the reaction will be

• 100 kJ mol^-1

• 200  kJ mol^-1

• 300 kJ mol^-1

• 175 kJ mol^-1

A radioactive sample is emitting 64 times radiations than non-hazardous limit. If its half life is 2h, after what time it become non-hazardous?

• 16h

• 12h

• 8h

• 4h

493.

Order of reaction is decided by

• molecularity

• pressure

• temperature

• mechanism of reaction as well as relative concentration of reactants

Half-life of a reaction is found to be inversely proportional to the cube of initial concentration. The order of reaction is

• 5

• 2

• 4

• 3

A chemical reaction was carried out at 300 K and 280 K. The rate constants were found to be K₁ and K₂ respectively. Then

• K₂ ≈ 0.25 K₁

• K₂ ≈ 0.5 K₁

• K₂ ≈ 4 K₁

• K₂ ≈ 2 K₁

Kinetic theory of gases presumes that collision between the molecules to be perfectly elastic because

• collisions will not split the molecule

• the molecules are tiny

• the molecules are rigid

• the temperature remains constant irrespective of collisions

If E_a = 30 kcal mol^-1 ,what is the effect on rate constant of a reaction for 10°C rise in temperature? It will increase

• three-fold

• two-fold

• three and half-fold

• four-fold

In the case of a radio isotope the value of T_1/2 and λ are identical in magnitude. The value is

• 0.693

• (0.693)^1/2

• 1/ 0.693

• (0.693)²

For gaseous reaction, the following data is given

A → B, k₁ = 10¹⁵ e^-2000/T

C → D, k₂ = 10¹⁴ e^-1000/T

The temperature at which k₁ = k₂ is

• 2000 K

• 868.8 K

• 434.2 K

• 1000 K

The conversion of cis-1, 2-dichloroethene to trans-1, 2-dichloroethene is an example of

• pseudo-unimolecular reaction

• the reaction having order between 1 and 2

• unimolecular reaction

• The conversion is spontaneous so zero-order reaction.