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)

A physician wishes to prepare a buffer solution at pH=3.58 that efficiently resist changes in pH yet contains only small concetration of the buffering agents. Which one of the following weak acid together with its sodium salt would be best to use ?           [1997]

1. m-chlorobenzoic acid (pK_a = 3.98)

2. p-chlorocinnamic acid (pK_a = 4.41)

3. 2,5-dihydroxy benzoic acid (pK_a = 2.97)

4. Acetoacetic acid (pK_a = 3.58)

One mole of ethyl alcohol was treated with one mole of acetic acid at 25$°$C. 2/3 of the acid changes into ester at equilibrium. The equilibrium constant for the reaction will be:

1. 1                   

2. 2

3. 3                   

4. 4

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

Aqueous solution of acetic acid contains                                                   

1. CH₃COO^- and H⁺

2. CH₃COO^-, H₃O⁺ and CH₃COOH

3. CH₃COO^-, H₃O⁺ and H⁺

4. CH₃COOH, CH₃COO^- and H⁺

The equilibrium, 2SO₂ (g) + O₂ (g) $\rightleftharpoons$2SO₃ (g)

shifts forward if:

1. a catalyst is used

2. an absorbent is used to remove SO₃ as soon as it is formed

3. small amounts of reactants are used

4. none of the above

The pH of blood is maintained by CO₂ by and H₂CO₃ in the body and chemical constituents of blood. This phenomenon is called:

1. colloidal                           

2. buffer action

3. acidic                               

4. salt balance