Ionic Equilibrium Test

Result

Ionic Equilibrium Test - 8

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Weekly Quiz Competition

Question 1
1 / -0

10^-2mole of NaOH was added to 10 litre of water. The pH will change by

A
4

B
3

C
11

D
7

Solution

pH_new = 11, Change in pH = 4
Question 2
1 / -0

If an acidic indicator HIn Ionizes as HIn ⇌ H⁺ + In^– . To which maximum pH value its solution has distinct colour characteristic of HIn?

A
pK_in^–1

B
pK_in ± 1

C
pK_in

D
7

Solution

For colour characteristic of H indicator

Indicator’s colour range

pH = pKln ± 1
Question 3
1 / -0

The H⁺ ion concentration in 0.001M CH₃CO₂H(K_a= 1.8 × 10^-5) is 1.34 × 10^-4 g ion/L. The H⁺ ion concentration if 0.164g of CH₃CO₂Na is added to a litre of 0.001M CH₃CO ₂H will be

A
9 × 10⁻⁶

B
18 × 10⁻⁶

C
4.5 × 10⁻⁶

D
5 × 10⁻⁶

Solution

= 4.74 + 0.3010 = 5.0457 = log[H⁺]

⇒ [H⁺ ] = 9 × 10^–6
Question 4
1 / -0

What is the minimum pH required to prevent the precipitation of ZnS in a solution that is 0.01 M ZnCl₂ and saturated with 0.10 M H₂S ?

[Given K_sp = 10^–21 , ^K_a₁ × ^K_a₂ = 10^–20]

A
0

B
1

C
2

D
4

Solution
Question 5
1 / -0

Ammoniacal solution of Ag⁺ + Acidified solution of N₂H₄ → ppt of (X)

A
(X) is Ag

B
(X) is Ag₂O

C
(X) is AgNH₂

D
(X) is Ag₂SO₄

Solution

4[Ag(NH₃)₂]⁺ + H₂N – NH₂. H₂SO₄ → 4Ag↓ + N₂ + 6NH4⁺ + 2NH₃ + SO₄^2–
Question 6
1 / -0

100 ml solution (I) of buffer containing 0.1(M) HA and 0.2 (M) A^– , is mixed with another solution (II) of 100 ml containing 0.2(M) HA and 0.3(M) A^–

After mixing what is the pH of resulting solution ? Given pK_a of HA = 5

A
5 – log 5/3

B
5 + log 5/3

C
5 + log 2/5

D
5 – log 5/2

Solution

After mixing total moles of

A^– = 100 × 0.2 × 10^–3 + 100 × 0.3 × 10^–3 = 100 × 10^–3× 0.5 moles

After mixing total moles of

HA = 100 × 0.1 × 10^–3 + 100 × 0.2 × 10^–3

= 100 × 0.3 × 10^–3 moles

After mixing resulting pH = 5 + log 5/3
Question 7
1 / -0

Which of the following is/are soft bases?

H₂O, H^– , CO,CO₂, C₂H₄, CN^–

A
C₂H₄

B
H^– ,CN^–, CO

C
H^– , CN^– , CO, C₂H₄

D
H^–, CO, CO₂, C₂H₄

Solution

Soft bases have the donor atom of highly polarisable and they preferably combine with the metal ions of lower oxidation states.
Question 8
1 / -0

Calcium lactate is a salt of weak organic acid and strong base represented as Ca (LaC)₂ . A saturated solution of Ca (LaC)₂ contains 0.6 mole in 2 litre solution. pOH of solution is 5.60. If 90% dissociation of the salt takes place, then what is pK_a of lactic acid ?

A
2.8 – log (0.54)

B
2.8 + log (0.54)

C
2.8 + log (0.27)

D
None of these

Solution
Question 9
1 / -0

Fixed volume of 0.1 M benzoic acid (pK_a = 4.2) solution is added into 0.2 M sodium benzoate solution and formed a 300 ml, resultant acidic buffer solution. If pH of this buffer solution is 4.5 then find added volume of benzoic acid -

A
100 ml

B
150 ml

C
200 ml

D
None of these

Solution
Question 10
1 / -0

The Ksp of FeS = 4 × 10^–19 at 298 K. The minimum concentration of H⁺ ions required to prevent the precipitation of FeS from a 0.01 M solution Fe²⁺ salt by passing H₂S is –

A
1.6 × 10^–3 M

B
2.5 × 10^–4M

C
2.0 × 10^–2 M

D
1.2 × 10^–4 M

Solution

In order to precipitate FeS, [S^–2] required is 4 × 10^–17 M from 0.01 M Fe²⁺ salts