Chemical Equilibrium : Chemistry

 Q.1. What is incorrect about buffer solution ?

A) It contains a weak acid and its conjugate base.

B) It contains a weak base and its conjugate acid

C) It shows change in pH on adding small amount of acid or base

D) All of the above

Explanation-

Buffer resist any change in pH on adding small amount of acid or base,

Q.2. Which of the following species are Lewis acids ?

(I) 

(II) 

(III) 

(IV)  

A) (I) and (II)

B) (III) and (IV)

C) (II) and (IV)

D) (I), (II) and (IV)

Explanation-

 and  are Lewis acids because they act as electron pair acceptors but  and   are Lewis bases because they act as electron pair donors.

Q.3.  Initial concentration of P is equal to that of Q. The equilibrium concentration of P and R equal . K is equal to 

A) 0.08

B) 0.8

C) 8

D)  

Explanation-

Let initial concentration of P and Q are equal and at equilibrium x concentration of P reacts , then 

 

Q,4,  A chemical reaction  is said to be in equilibrium when 

A) Complete conversion of A to B has taken place

B) Conversion of A to B is only 50% complete 

C) Only 10% conversion of A to B has taken place

D) The rate of transformation of A to B is just equal to rate of transformation of B to A in the system

Explanation-

At equilibrium , rate of forward reaction is equal to rate of back forward reaction is equal to rate of backward reaction .

Q.5.  Two mole of PCI are heated in a hosed vessel of 2 litre capacity . When the equilibrium is attained, 40%  of it has been found to be dissociated . What is K in mol/dm ?

A) 0.532

B) 0.266

C) 0.133

D) 0.174

Explanation-

 

Q.6.  4 moles of A are mixed with 4 moles of B , when 2 moles of C and D are formed at equilibrium according to the reaction , A+B   C+D the value of equilibrium constant is 

A) 4

B) 1

C) 1/2

D) 1/4

Explanation-

 

Q.7.  In which of the following cases, the reaction goes farthest to completion 

A) K = 10 

B) K = 10 

C) K = 10

D) K = 10 

Explanation-

Greater the value of K, reaction is favored in forward direction.

Q.8.  The equilibrium constant , K for the reaction ,   at room temperature is 2.85 and that at 698 K is  . This implies that 

A) HI is an acidic compound

B) HI is very stable at room temperature 

C) HI is relatively less stable than H and I

D) HI is resonance stabilized 

Explanation-

Equilibrium constant K is decreasing with increasing temperature. It shows that reaction is exothermic in forward direction which ultimately means that energy of HI is more than that of . Hence, HI relatively less stable than .

Q.9.  The gaseous reaction A+B  2 C + D +q is most favored at

A) High temperature and low pressure 

B) Low temperature and low pressure 

C) Low temperature and High pressure 

D) High temperature and high pressure 

Explanation-

 The given reaction is endothermic and accompanied with increase in number of moles. Thus, favored at low temperature and low pressure.

Q.10. In a lime kiln , to get higher yield of CO , the measure that can be taken is 

A) To maintains high temperature 

B) To pump out CO

C) To remove CaO

D) To add more CaCO 

Explanation-

 Removal of  from the reaction mixture shift the reaction in a direction in which more of  is formed