21.

Rate of a reaction can be expressed by Arrhenius equation as K= Ae^-E/RT In this equation, E represents

• the energy above which all the colliding molecules will react

• the energy below which colliding molecules will not react

• the total energy of the reacting molecules at a temperature, T

• the total energy of the reacting molecules at a temperature, T

The following mechanism has been proposed for the reaction of NO with Br2 to form NOBr
NO(g) Br₂ (g) ⇌ NOBr₂ (g)
NOBr₂ (g) NO(g)→ 2NOBr(g)
If the second step is the rate determining step, the order of the reaction with respect to NO(g) is

• 1

• 0

• 3

• 3

Hydrogen bomb is based on the principle of

• Nuclear fission

• Natural radioactivity

• Nuclear fusion

• Nuclear fusion

Consider an endothermic reaction, X → Y with the activation energies E_b and E_f for the backward and forward reactions, respectively. In general

• E_b < E_f

• E_b > E_fEb > Ef

• E_b = E_f

• E_b = E_f

A reaction involving two different reactants can never be

• Unimolecular reaction

• First order reaction

• second order reaction

• second order reaction

A schematic plot of In K_eq versus inverse of temperature for a reaction is shown below



The reaction must be

• exothermic

• endothermic

• one with negligible enthalpy change temperature

• one with negligible enthalpy change temperature

The photon of hard gamma radiation knocks a proton out of ²⁴₁₂Mg nucleus to form

• the isotope of parent nucleus

• the isobar of parent nucleus

• the nuclide
  

• the nuclide
  

t₁/4 can be taken as the time taken for the concentration of a reactant to drop to 3/4 of its initial value. If the rate constant for a first order reaction is K, the t₁/4 can be written as

• 0.10 / K

• 0.29 / K

• 0.69 / K

• 0.69 / K

An amount of solid NH₄HS is placed in a flask already containing ammonia gas at a certain temperature and 0.50 atm. Pressure. Ammonium hydrogen sulphide decomposes to yield NH₃ and H₂S gases in the flask. When the decomposition reaction reaches equilibrium, the total pressure in the flask rises to 0.84 atm. The equilibrium constant for NH₄HS decomposition at this temperature is

• 0.30

• 0.18

• 0.17

• 0.17

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

• 30 minutes

• 60 minutes

• 7.5 minutes

• 7.5 minutes