Multiple Choice QuestionsThe pH of a buffer solution made by mixing 25 mL of 0.02 M NH4OH and 25 mL of 0.2 M NH4Cl at 25° is pKb of NH4OH = 4.8)
5.8
8.2
4.8
3.8
B.
8.2
As a mixture of NH4OH and NH4Cl acts as a basic buffer, so its pH must be basic, i.e. greater than 7.
pOH = pKb + log
= 4.8 + log
= 4.8 × log 10
pOH = 4.8 + 1 = 5.8
pH = 14 - pOH = 14 - 5.8 = 8.2
Which one of the following statements is not correct?
The pH of 1.0 ×10-8 M HCl is less than 7.
The ionic product of water at 25°C is 1.0 ×10-14 mol2L-2
Cl- is a Lewis acid
Bronsted Lowry theory cannot explain the acidic character of AlCl3.
The pKa values of four carboxylic acids are given below. Identify the weakest carboxylic acid.
4.89
1.28
4.76
2.56
On increasing temperature, the equilibrium constant of exothermic and endothermic reactions, respectively
increases and decreases
decreases and increases
increases and increases
decreases and decreases
What is the pH of the NaOH solution when 0.04 g of it dissolved in water and made to 100 mL solution?
2
1
13
12
Which one of the following is correct with respect to basic character?
P(CH3)3 > PH3
PH3 > P(CH3)3
PH3 > NH3
PH3 = NH3
If the ionc product of Ni(OH)2 is 1.9× 10-15, the molar solubility of Ni(OH)2 in 1.0 M NaOH
1.9 × 10-18 M
1.9 × 10-13 M
1.9 × 10-15 M
1.9 × 10-15 M
40 mL of x M KMnO4 solution is required to react completely with 200 mL of 0.02 M oxalic acid solution in acidic medium. The value of x is
0.04
0.01
0.03
0.02
At 400 K, in a 1.0 L vessel, N2O is allowed to attain equilibrium, N2O4 (g) 2NO2 (g)
At equilibrium, the total pressure is 600 mm Hg, when 20% of N2O4 is dissociated. The value of KP for the reaction is
50
100
150
200
In which of the following salts, only cationic hydrolysis is involved?
CH3COONH4
CH3COONa
NH4Cl
Na2SO4
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