chemistry : class11 Ammonium Hydroxide and Ammonium Ion : Common ion effect : Equilibrium MCQ Questions and Answers
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Ammonium Hydroxide and Ammonium Ion
MCQ questions and answers.
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MCQ Questions
1. Ammonium hydroxide ionizes in water according to which equilibrium?
A.
NH4OH ⇌ NH4+ + OH−
B.
NH4OH ⇌ NH3+ + H−
C.
NH4OH ⇌ NH4− + OH+
D.
NH4OH ⇌ N2 + H2O
Correct Answer:
NH4OH ⇌ NH4+ + OH−
Explanation:
Ammonium hydroxide is a weak base and partially ionizes in water to form ammonium ions and hydroxide ions.
2. Which ion is common to ammonium hydroxide and ammonium chloride?
A.
Cl−
B.
OH−
C.
NH4+
D.
H+
Correct Answer:
NH4+
Explanation:
Ammonium hydroxide produces NH4+ in solution, and ammonium chloride dissociates to give NH4+ and Cl−. Therefore, NH4+ is the common ion.
3. What happens to the ionization of ammonium hydroxide when ammonium chloride is added to its solution?
A.
It increases greatly
B.
It decreases
C.
It remains exactly unchanged
D.
It becomes complete
Correct Answer:
It decreases
Explanation:
Ammonium chloride adds NH4+ ions, which are common ions. According to Le Chatelier's principle, the equilibrium shifts left and the ionization of NH4OH decreases.
4. The common ion effect in an ammonium hydroxide solution is caused by the addition of which compound?
A.
Sodium chloride
B.
Ammonium chloride
C.
Potassium nitrate
D.
Calcium sulfate
Correct Answer:
Ammonium chloride
Explanation:
Ammonium chloride dissociates to produce NH4+, which is already present from the ionization of ammonium hydroxide.
5. When ammonium chloride is added to ammonium hydroxide, the concentration of which ion increases directly?
A.
NH4+
B.
OH−
C.
O2−
D.
H2+
Correct Answer:
NH4+
Explanation:
Ammonium chloride dissociates in water into NH4+ and Cl−, so the concentration of NH4+ increases directly.
6. In the equilibrium NH4OH ⇌ NH4+ + OH−, adding NH4+ shifts the equilibrium in which direction?
A.
To the right
B.
To the left
C.
In both directions equally
D.
It removes the equilibrium completely
Correct Answer:
To the left
Explanation:
Adding the product NH4+ causes the equilibrium to shift left, reducing the ionization of ammonium hydroxide.
7. Why is ammonium hydroxide considered a weak base?
A.
It does not dissolve in water
B.
It ionizes only partially in water
C.
It contains no nitrogen
D.
It produces only chloride ions
Correct Answer:
It ionizes only partially in water
Explanation:
Ammonium hydroxide is a weak base because only a small fraction of its molecules ionize into NH4+ and OH− in aqueous solution.
8. Which species is suppressed when ammonium chloride is added to ammonium hydroxide?
A.
The ionization of NH4OH
B.
The formation of NH4Cl
C.
The dissociation of water into oxygen
D.
The formation of nitrogen gas
Correct Answer:
The ionization of NH4OH
Explanation:
The added NH4+ from ammonium chloride suppresses the ionization of NH4OH through the common ion effect.
9. A solution contains ammonium hydroxide and ammonium chloride. Which ion is present because of both solutes?
A.
NH4+
B.
Cl−
C.
OH− only
D.
NO3−
Correct Answer:
NH4+
Explanation:
Ammonium hydroxide ionizes to form NH4+, while ammonium chloride dissociates to form NH4+ and Cl−. Thus, NH4+ comes from both solutes.
10. What is the main result of the common ion effect on ammonium hydroxide?
A.
Increase in its ionization
B.
Suppression of its ionization
C.
Conversion into a strong acid
D.
Removal of all NH4+ ions
Correct Answer:
Suppression of its ionization
Explanation:
The NH4+ ion supplied by ammonium chloride shifts the NH4OH ionization equilibrium to the left, thereby suppressing its ionization.
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