Collision Theory

Q. An exothermic chemical process occurs in two steps as follows:
(i) $A+B\to X$ (slow)
(ii) $X\to AB$ (fast)
The energy profile that best suits this process is:

1. 
2. 
3. 
4. 

Q.

Species that are formed in one step of reaction mechanism and used up in another step are called

1. catalysts

2. intermediates

3. inhibitors

4. activated complexes

Q. Chemical reactions with very high $E_a$ values are generally:

1. Very fast
2. Very slow
3. Moderately fast
4. Spontaneous

Q.

In most cases, for a rise of 10K temperature, the rate constant is doubled or tripled. This is due to the reason that ?

1. Collision frequency increases by a factor 2 to 3

2. Fraction of molecules possessing threshold energy increases by a factor of 2 to 3

3. Activation energy is lowered by a factor of 2 to 3

4. None of these

Q. Reaction A + B $\to$ C + D + 38 kcal, has activation energy 20 kcal, Activation energy for reaction C + D $\to$ A + B is

1. 20 kcal
2. -20 kcal
3. 58 kcal
4. 18 kcal

Q. Match the following

$\begin{array}{cccc}a)& a& \left(i\right)& Activationenergyofforwardreaction\\ b)& b& \left(ii\right)& Changeinenthalpy\\ c)& c& \left(iii\right)& Activationenergyofbackwardreaction\\ d)& d& \left(iv\right)& PotentialEnergyofReactants\\ e)& e& \left(v\right)& PotentialenergyofProducts\end{array}$

1. a – (v) b – (iv) c – (i) d – (iii) e – (ii)
2. a – (i) b – (iv) c – (v) d – (iii) e – (ii)
3. a – (iv) b – (i) c – (v) d – (iii) e – (ii)
4. a – (iv) b – (i) c – (v) d – (ii) e – (iii)

Q. An exothermic reaction A $\to$ B has an activation energy of 17 kJ per mole of A. The heat of reaction is 40 KJ. The activation energy for the reverse reaction B $\to$ A is

1. 23 kJ
2. 97 kJ
3. 57 kJ
4. 17 kJ