The hydrogen ion concentration of a 10^-8 M HCl aqueous solution at 298 K (K_w =10-14) is       

1. 1.0 x10^-6 M                     

2. 1.0525 x 10^-7 M

3. 9.525 x 10^-8 M               

4. 1.0 x10^-8 M

2 mole of PCl₅ were heated in a closed vessel of 2 litre capacity. At equilibrium 40% of PCl₅ dissociated into PCl₃ and Cl₂. The value of the equilibrium constant is :

1. 0.267

2. 0.53

3. 2.63

4. 5.3

The relation for calculating pH of a solution containing weak acid and its salt is:

1. pH = pK_a + log$\frac{[\mathrm{Conjugate} \mathrm{Base}]}{\left[\mathrm{Acid}\right]}$

2. pH = pK_a - log$\frac{[\mathrm{Conjugate} \mathrm{Base}]}{\left[\mathrm{Acid}\right]}$

3. pH = pK_a + log$\frac{[\mathrm{Conjugate} \mathrm{Base}]}{\left[\mathrm{Salt}\right]}$

4. pOH = pK_a - log$\frac{\left[\mathrm{Acid}\right]}{[\mathrm{Conjugate} \mathrm{Base}]}$

The equilibrium constant Br₂ $\rightleftharpoons$2Br at 500 K and 700 K are 10^-10 and 10^-5 respectively. The reaction is:

(a) endothermic                                  (b) exothermic

(c) fast                                               (d) slow

1. a,b

2.c,b

3.a,d

4 c,d

Solubility of a gas in liquid increases on:

1. Addition of a catalyst

2. Increasing the pressure

3. Decreasing the pressure

4. Increasing the temperature

The molecule that is least likely to act as a Lewis base is:     

1. CO         

2. \(F^{-}\)         

3. AlCl₃      

4. PF₃

Solubility of MX₂ type electrolytes is 0.5x10^-4 mol/L, then the K_sp of electrolytes is :         

1. 5 x 10^-12

2. 25 x 10^-10

3. 1 x 10^-13

4. 5 x 10^-13

The ionisation constant of ammonium hydroxide is 1.77 x 10^-5 at 298 K. Hydrolysis constant of ammonium chloride is

1. 5.65 x 10^-10                     

2. 6.50 x 10^-12

3. 5.65 x 10^-13                     

4. 5.65 x 10^-12

For a given solution pH = 6.9 at 60$°$C, where K_w=10^-12. The solution is:

1. acidic                                         

2. basic

3. neutral                                         

4. unpredictable

In a buffer solution containing equal concentration of B^- and H B, the K_b for B^- is 10^-10. The pH of buffer solution is 

1. 10

2. 7

3. 6

4. 4