341.

The pH of a 0.1 molar solution of the acid HQ is 3. The value of the ionisation constant, K_a of this acid is

• 3 x 10^–1

• 1 x 10^–3

• 1 x 10^—5

• 1 x 10^—5

Consider the reaction:
Cl₂(aq) + H₂S(aq) → S (s) + 2H⁺ (aq) + 2Cl^- (aq)
The rate equation for this reaction is
I. Cl₂ + H₂S → H⁺ +Cl^- + Cl⁺ +HS^-
II. H₂S ⇌ H⁺ + HS^- (fast equilibrium)
Cl₂ + HS^- → 2Cl^- + H⁺ + S (slow)

• II only

• Both (I) and (II)

• Neither (I) nor (II)

• Neither (I) nor (II)

Three reactions involving H₂PO₄^- are given below
I. H₃PO₄ + H₂O → H₃O⁺ + H₂PO₄^-
II. H₂PO₄^- + H₂O→ HPO₄^2- + H₃O⁺
III. H₂PO₄^- + OH^- → H₃PO₄  + O^2-
In which of the above does H₂PO₄^- act  as an acid

• (II) only

• (I) and (II)

• (III) only

• (III) only

In aqueous solution the ionization constants for carbonic acid are
K₁ = 4.2 x 10^-7 and K₂ = 4.8 x 10^-11.
Select the correct statement for a saturated 0.034 M solution of the carbonic acid.

• The concentration of CO₃^2- is 0.034 M

• The concentration of CO₃^2- is greater than that of HCO₃^-

• The concentration of H⁺ and HCO₃^- are approximately equal

• The concentration of H⁺ and HCO₃^- are approximately equal

The correct order of increasing basicity of the given conjugate bases (R = CH₃) is

At 25°C, the solubility product of Mg(OH)₂ is 1.0 × 10^–11. At which pH, will Mg²⁺ ions start precipitating in the form of Mg(OH)₂ from a solution of 0.001 M Mg²⁺ ions?

• 9

• 10

• 11

• 11

p_Ka of a weak acid (H_A) and pKb of a weak base (BOH) are 3.2 and 3.4, respectively. The p_H of their salt (AB) solution is

• 7.2

• 6.9

• 7.0

• 7.0

In the following reactions, ZnO is respectively acting as a/an :
(a) ZnO + Na₂O → Na₂ZnO₂
(b) ZnO + CO₂ → ZnCO₃

• base and acid

• base and base

• acid and acid

• acid and acid

The equilibrium constants K_P1 and K_P2 for the reactions X ⇌2Y and Z ⇌ P + Q, respectively are in the ratio of 1 : 9. If the degree of dissociation of X and Z be equal then the ratio of total pressure at these equilibria is

• 1:1

• 1:36

• 1:9

• 1:9

For the following three reactions a, b and c, equilibrium constants are given

a. CO (g) + H₂O (g) ⇌ CO₂ (g)+ H₂ (g); K₁
b. CH₄(g) + H₂O (g) ⇌ CO (g) + 3H₂ (g); K₂
c. CH₄(g) + 2H₂O (g) ⇌ CO₂ (g) + 4H₂ (g); K₂
Which of the following relations is correct?

• K₁√K₂ = K₃

• K₂K₃ = K₁

• K₃ = K₁K₂

• K₃ = K₁K₂