Equilibrium · Question 47

Identify the correct order of solubility in aqueous medium.

1. Na2S > CuS > ZnS
2. Na2S > ZnS > CuS
3. CuS > ZnS > Na2S
4. ZnS > Na2S > CuS

Accumulation of lactic acid (HC3H5O3), a monobasic acid in tissues leads to pain and a feeling of fatigue. In a 0.10 M aqueous solution, lactic acid is 3.7% dissociated. The value of dissociation constant, Ka, for this acid will be

1. 1.4 10-5
2. 1.4 10-4
3. 3.7 10-4
4. 2.8 10-4

At 100 the Kw of water is 55 times its value at 25 . What will be the pH of neutral solution? (log 55 = 1.74)

1. 7.00
2. 7.87
3. 5.13
4. 6.13

The values of Ksp of CaCO3 and CaC2O4 are 4.7 10-9 and 1.3 10-9 respectively at 25 . If the mixture of these two is washed with water, what is the concentration of Ca2+ ions in water ?

1. 5.831 10-5 M
2. 6.856 10-5 M
3. 3.606 10-5 M
4. 7.746 10-5 M

The dissociation constant of weak acid is 1 10-4. In order to prepare a buffer solution with a pH = 5, the [Salt]/[Acid] ratio should be

1. 4 : 5
2. 10 : 1
3. 5 : 4
4. 1 : 10

Given that the equilibrium constant for the reaction, 2SO2(g) + O2(g) 2SO3(g) has a value of 278 at a particular temperature. What is the value of the equilibrium constant for the following reaction at the same temperature ? SO3(g) SO2(g) + 12O2(g)

1. 1.8 10-3
2. 3.6 10-3
3. 6.0 10-2
4. 1.3 10-5

Given the reaction between 2 gases represented by A2 and B2 to give the compound AB(g), A2(g) + B2(g) 2AB(g) At equilibrium, the concentration of A2 = 3.0 10-3 M, of B2 = 4.2 10-3 M, of AB = 2.8 10-3 M If the reaction takes place in a sealed vessel at 527 , then the value of Kc will be

1. 2.0
2. 1.9
3. 0.62
4. 4.5

pH of a saturated solution of Ba(OH)2 is 12. The value of solubility product (Ksp) of Ba(OH)2 is

1. 3.3 10-7
2. 5.0 10-7
3. 4.0 10-6
4. 5.0 10-6

Equimolar solutions of the following substances were prepared separately. Which one of these will record the highest pH value ?

1. BaCl2
2. AlCl3
3. LiCl
4. BeCl2

Buffer solutions have constant acidity and alkalinity because

1. these give unionised acid or base on reaction with added acid or alkali
2. acids and alkalies in these solutions are shielded from attack by other ions
3. they have large excess of H+ or OH- ions
4. they have fixed value of pH