Ionic Equlibrium Test

Result

Ionic Equlibrium Test - 9

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Weekly Quiz Competition

Question 1
4 / -1

The range of most suitable indicator which should be used for titration of X^-Na⁺ (0.1 M, 10 ml) with 0.1 M HCl should be ( Given : k_b(X^-) = 10^-6 )

A
2-3

B
3-5

C
6-8

D
8-10

Solution

NaX + HCl → NaCl + HX
[HX] at equivalent point = 0.05

Range of Indicator = 3 to 5
Question 2
4 / -1

How many gm of solid NaOH must be added to 100 ml of a buffer solution which is 0.1 M each w.r.t. Acid HA and salt Na⁺ A^- to make the pH of solution 5.5. Given pK_a(HA) = 5 (Use antilog (0.5)= 3.16)

A
2.08 × 10^-1

B
3.05 × 10^-3

C
2.01 × 10^-2

D
None of these

Solution

Suppose x m. mole NaOH was added
Question 3
4 / -1

The solubility of A₂X₃ is y mol dm^-3. Its solubility product is

A
6y²

B
64 y⁴

C
36 y⁵

D
108 y⁵

Solution

K_sp = (2y)² (3y)³
K_sp = 108y⁵
Question 4
4 / -1

If K_sp for HgSO₄ is 6.4 × 10^-5, then solubility of this substance in mole per m³is

A
8 × 10^-3

B
6.4 × 10^-5

C
8 × 10^-6

D
None of these

Solution

Ksp = S²
⇒ 6.4 × 10^–5 = S²
⇒ S = 8 × 10^–3 mole/L
S = 8 × 10^–3 × 10³ mole/m³
⇒ S = 8 mole/m³
Question 5
4 / -1

Which of the following in most soluble in water ?

A
MnS (K_sp = 8 × 10^-37)

B
ZnS(K_sp = 7 × 10^-16)

C
Bi₂S₃(K_sp = 1 × 10^-72)

D
Ag₃(PO₄)(K_sp = 1.8 × 10^-18)

Solution

Calculate the solubility ‘s’ for each option, Higher the value of ‘s’ Higher the solubility.
Question 6
4 / -1

1 M NaCl and 1 M HCl are present in an aqueous solution. The solution is

A
Not a buffer solution and with pH < 7

B
Not a buffer solution with pH > 7

C
A buffer solution with pH < 7

D
A buffer solution with pH > 7

Solution

NaCl + HCl : Not the Buffer and Solution is acidic due to HCl.
⇒ pH < 7.
Question 7
4 / -1

The pK_a of a weak acid (HA) is 4.5. The pOH of an aqueous buffered solution of HA in which 50% of the acid is ionized is:

A
4.5

B
2.5

C
9.5

D
7.0

Solution

50% ionised ⇒ [Salt] = [Acid]
⇒ pH = pKa = 4.5
⇒ pOH = 9.5
Question 8
4 / -1

The precipitate of CaF₂ (K_sp = 1.7 × 10^-10) is obtained when equal volumes of the following are mixed

A
10^-4 M Ca³⁺ + 10^-4 M F^-

B
10^-2 M Ca²⁺ + 10^-3 M F^-

C
10^-5 M Ca²⁺ + 10^-3 M F^-

D
10^-3 M Ca²⁺ + 10^-5 M F^-

Solution

For ppt Q_sp > K_sp
CaF₂→ Ca²⁺+2F^–
Q_sp = (Ca²⁺) (F^–)²
(A) Q_sp = 12.5 × 10^–14
(B) Q_sp = 12.5 × 10^–10
(C) Q_sp = 12.5 × 10^–13
(D) Q_sp = 12.5 × 10^–15
Only (B) option will get precipitate.
Question 9
4 / -1

pH of saturated solution of silver salt of monobasic acid HA is found to be 9.
Find the K_sp of sparingly soluble salt Ag A(s).
Given : K_a(HA) = 10^-10

A
1.1 × 10^-11

B
1.1 × 10^-10

C
10^-12

D
None of these

Solution

K_sp = S (S–X) = 11 × 10^–6 × 10^–6
= 1.1 × 10–11
Question 10
4 / -1

When equal volumes of the following solutions are mixed, precipitation of AgCl (K_sp = 1.8 × 10^-10) will occur only with:

A
10^-4 M (Ag⁺) and 10^-4M(Cl^-)

B
10^-5 M (Ag⁺) and 10^-5M(Cl^-)

C
10^-6 M (Ag⁺) and 10^-6M(Cl^-)

D
10^-10 M (Ag⁺) and 10^-10M(Cl^-)

Solution