Three reactions involving ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}$ are given below:

(i) H₃PO₄ + H₂O $\to$H₃O⁺ + ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}$

(ii) ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}$ + H₂O $\to$${\mathrm{HPO}}_4^{2-}$ + H₃O⁺

(iii) ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}$ + OH^- $\to$H₃PO₄ +O^2-

In which of the above does ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}$ act as an acid?

1. (i) only                                 

2. (ii) only

3. (i) and (ii)                           

4. (iii) only

Which of the following is most soluble in water?

1. MnS (K_sp = 8x10^-37)         

2. ZnS (K_sp = 7x10^-16)

3. Bi₂S₃ (K_sp = 1x10^-70)       

4. Ag₂S (K_sp = 6x10^-51)

The compound that does not act as Lewis acid is:

1. AlCl₃                                           

2. BF₃

3. NH₃                                             

4. FeCl₃

For which salt the pH of its solution does not change with dilution?

1. NH₄Cl                           

2. CH₃COONH₄

3. CH₃COONa                   

4. None of these

For a sparingly soluble salt A^pB^q, the relationship of its solubility product (L_s) with its solubility (s) is:

1. L_s =s^p+q.p^p.q^q                           

2.  L_s =s^p+q.p^q.q^p  

3. L_s =s^pq.p^p.q^q                            

4.  L_s = s^pq.(pq)^p+q

For the reaction, N₂ + 3H₂ $\rightleftharpoons$2NH₃ in a vessel, after the addition of an equal number of mole of N₂ and H₂, the equilibrium state is formed. Which of the following is correct?

1. [H₂] = [N₂]                               

2. [H₂] < [N₂]     

3. [H₂] > [N₂]                                 

4. [H₂] > [NH₃]      

The conjugate base of [Al(H₂O)₃(OH)₃] is:

1. [Al(H₂O)₃(OH)₂]⁺                           

2. [Al(H₂O)₃(OH)₂O]^-

3. [Al(H₂O)₃(OH)₃]^-                           

4.  [Al(H₂O)₂(OH)₄]^-

For NH₄HS(s) $\rightleftharpoons$NH₃ (g) + H₂S(g), the observed pressure for reaction mixture in equilibrium is 1.12 atm at 106$°$C. The value of K_p for the reaction is:

1. 3.136 atm²                           

2. 0.3136 atm²

3. 31.36 atm²                           

4. 6.98 atm²

Which oxide of nitrogen is the most stable?

1. 2NO₂(g) $\rightleftharpoons$N₂(g) + 2O₂(g);         K=6.7x10¹⁶ mol litre^-1

2. 2NO(g) $\rightleftharpoons$N₂(g) + O₂(g);            K=2.2x10³⁰ mol litre^-1

3. 2N₂O₅(g) $\rightleftharpoons$2N₂(g) + 5O₂(g);      K=1.2x10³⁴ mol^-5 litre^-5

4. 2N₂O(g) $\rightleftharpoons$2N₂(g) + O₂(g);         K=3.5x10³³ mol litre^-1

On adding A to the reaction at equilibrium,  AB(s) $\rightleftharpoons$ A(g) + B(g), the new equilibrium concentration of A becomes double, the equilibrium concentration of B would become:

1. 1/2 of its original value

2. 1/4 of it s original value

3. 1/8 of its original value

4. twice of its original value