The relation for calculating pH of a weak base is:

1. pH =pK_w -1/2 pK_b + 1/2 logc

2. pH =pK_w +1/2 pK_b - 1/2 logc

3. pH =pK_w -1/2 pK_a + 1/2 logc

4. none of the above

In a closed container of 1 dm³, 8 moles of \(AB_3\)​ gas reach equilibrium following the reaction:
\(2 \mathrm{AB}_3(g) \rightleftharpoons \mathrm{~A}_2(g)+3 \mathrm{~B}_2(g)\)
What is the equilibrium constant when 2 moles of \(A_2\) are observed at equilibrium?

1. 72 mol²L^-2                     

2. 36 mol²L^-2 

3. 3 mol²L^-2                       

4. 27 mol²L^-2  

Which is Lewis base?

1. HCl               

2. HNO₃

3. HF               

4. NH₃

For a reversible reaction, if the concentrations of the reactants are doubled, the equilibrium constant will be                                                                                       

1. one-fourth                         

2. halved

3. doubled                             

4. the same

A buffer solution is prepared in which the concentration of NH₃ is 0.3 M and the concentration of ${\mathrm{NH}}_4^{+}$ is 0.20 M. If the equilibrium constant, K_b for NH₃ equals 1.8x10^-5, what is the pH of this solution?                                                                                       

1. 9.43                             

2. 11.72

3. 8.73                               

4. 9.08

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

1. CO         

2. \(F^{-}\)         

3. AlCl₃      

4. PF₃

For a hypothetical equilibrium:

$4\mathrm{A} + 5\mathrm{B} \stackrel{ }{\rightleftharpoons } 4\mathrm{x} + 6\mathrm{y}$;
the equilibrium constant K_c has the unit:

1. mol² litre^-2

2. litre mol^-1

3. litre² mol^-2

4. mol litre^-1

Calculate the pOH of a solution at 25$°$C that contains 1x10^-10 M of hydronium ion.        

1. 7.00                         

2. 4.00

3. 9.00                         

4. 1.00

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

For which reaction does the equilibrium constant depend on the units of concentration?

1. NO (g) $\rightleftharpoons$$\frac{1}{2}$N₂ (g) + $\frac{1}{2}$O₂ (g)

2. Zn (s) + Cu²⁺ (aq) $\rightleftharpoons$ Cu(s) + Zn²⁺ (aq)

3. C₂H₅OH (l) + CH₃COOH (l) $\rightleftharpoons$CH₃COOC₂H₅ (l) + H₂O (l)

4. COCl₂ (g) $\rightleftharpoons$ CO(g) + Cl₂ (g)