In a reversible reaction, the catalyst

• increases the activation energy of the backward reaction

• increases the activation energy of the forward reaction

• decreases the activation energy of both, forward and backward reaction 

• decreases the activation energy of forward reaction

The reaction, 2SO₂(g) + O₂(g) $\rightleftharpoons$2SO₃ (g) is carried out in a 1 dm³ vessel and 2 dm³ vessel separately. The ratio of the reaction velocities will be

• 1:8

• 1:4

• 4:1

• 8:1

A wooden box excavated from Indus valley had an activity of 1.18 × 10¹³ disintegration per minute per gm of carbon. What is the approximate age of this civilisation?

• 4000 years

• 5700 years

• 8100 years

• 6000 years

For a reaction if K_p > K_c, the forward reaction is favoured by

• low pressure

• high pressure

• high temperature

• low temperature

Which one of the following is wrongly matched?

• Sponification of CH₃COOC₂H₅ - Second order reaction

• Hydrolysis of CH₃COOCH₃ - pseudo unimolecular reaction

• Decompostion of H₂O₂ - First order reaction

• Combination of H₂ and Br₂ to give HBr - first order reaction

The velocity constant of a reaction at 290 K was found to be 3.2 ×10^-3 s^-1. When the temperature is raised to 310 K, it will be about

• 6.4 × 10^-3

• 3.2 × 10^-4

• 9.6 × 10^-3

• 1.28 × 10^-2

Which of these does not influence the rate of reaction?

• Nature of the reactants

• Concentration of the reactants

• Temperature of the reaction

• Molecularity of the reaction

208.

For the reaction A + B → C,it is found that doubling the concentration of A increases the rate by 4 times, and doubling the concentration of B doubles the reaction rate. What is the overall order of the reaction?

• 4

• 3/2

• 3

• 1

Chemical reactions with very high E_a values are generally :

• very fast

• very slow

• moderately fast

• spontaneous

A radioactive isotope has a half-life of 10 days. If today 125 mg is left over, what was its original weight 40 days earlier?

• 2 gm

• 600 mg 

• 1 gm

• 1.5 gm