pH of a solution of 10 mL 1N sodium acetate and 50 mL 2N acetic acid (K_a = 1.8 x 10^-5), is approximately :

• 4

• 5

• 6

• 7

The pH is less than 7, of the solution of :

• FeCl₃

• NaCN

• NaOH

• NaCl

213.

Dimethyl glyoxime gives a red precipitate with Ni²⁺, which is used for its detection. To get this precipitate readily the best pH range is

• < 1

• 2-3

• 3- 4

• 9- 11

The values of K_sp for CuS, Ag₂S and HgS are 10^-31, 10⁴², 10^-54 respectively. The correct order of their solubility in water is :

• AgS > HgS > CuS

• HgS > Cus > Ag₂S

• HgS > Ag₂S > Cus

• Ag₂S > CuS > HgS

For a gaseous reaction,

C₂H₄ + H₂ $\rightleftharpoons$ C₂H₆ ; $∆$H = -32.7 Kcal.

The concentration of C₂H₄ can be decreased by :

• increasing pressure

• increasing amount of H₂

• decreasing temperature

• all of these

PCl₅ was heated in a 10 dm³ container at 250°C

PCl₅(g) $\rightleftharpoons$ PCl₃(g) + Cl₂ (g)

0.1 mol PCl₅ and 0.2 mol Cl₂ was found at equilibrium. The equilibrium constant for the reaction is :

• 0.025

• 0.04

• 0.02

• 0.05

In the reaction,

H₂SO₄ + H₂O $\rightleftharpoons$ H₃O⁺ + HSO₄^-,

the conjugate acid of water is :

• H₃O⁺

• H₂O

• HSO₄^-

• SO₄^2-

At 80°C, distilled water has H⁺ ions concentration equal to 1 x 10^-6 mole/litre. The value of K_W at this temperature will be :

• 1 X 10^-6

• 1 X 10^-12

• 1 X 10^-9

• 1 X 10^-15

The pH of solution containing 0.10 M sodium acetate and 0.03 M acetic acid is :

(pK_a for CH₃COOH = 4.57)

• 4.09

• 6.09

• 5.09

• 7.09

The solubility of CuBr is 2 x 10^-4 mol/L at 25°C. The K_SP value for CuBr is :

• 4 x 10^-8 mol² L^-2

• 4 x 10^-4 mol² L^-2

• 4 x 10^-11 mol² L^-2

• 4 x 10^-15 mol² L^-2