Question

(i) \( \text{AgNO}_3 + \text{NaCl} \rightarrow \text{NaNO}_3 + \text{AgCl} \)
(ii) \( \text{K}_2\text{SO}_4 + \text{BaCl}_2 \rightarrow \text{BaSO}_4 + 2\text{KCl} \)
Which of the following options clearly describes both the reactions?

• A. (i) is double displacement, (ii) is displacement reaction.
• B. Both, (i) and (ii) are displacement reactions and precipitation reactions.
• C. Both, (i) and (ii) are double displacement reactions and precipitation reactions.
• D. (i) is displacement, (ii) is double displacement reaction.

Hint:

Double displacement reactions often result in precipitate formation when one product is insoluble.
Common precipitates: AgCl (white), BaSO\(_4\) (white), PbI\(_2\) (yellow), etc.

Answer 1

The Correct Option is C

Step 1: Understand the types of reactions.

• Double displacement reaction: A reaction where two compounds exchange their ions to form two new compounds. General form: \(AB + CD \rightarrow AD + CB\)
• Precipitation reaction: A reaction in which an insoluble solid (precipitate) is formed when two solutions are mixed.
• Displacement reaction: A reaction where a more reactive element displaces a less reactive element from its compound. General form: \(A + BC \rightarrow AC + B\)

Step 2: Analyze reaction (i).
\[ \text{AgNO}_3 + \text{NaCl} \rightarrow \text{NaNO}_3 + \text{AgCl} \]

• Ions exchange: \( \text{Ag}^+ \) combines with \( \text{Cl}^- \) to form AgCl, and \( \text{Na}^+ \) combines with \( \text{NO}_3^- \) to form NaNO\(_3\).
• This is a double displacement reaction.
• AgCl is insoluble in water and forms a white precipitate.
• This is also a precipitation reaction.

Step 3: Analyze reaction (ii).
\[ \text{K}_2\text{SO}_4 + \text{BaCl}_2 \rightarrow \text{BaSO}_4 + 2\text{KCl} \]

• Ions exchange: \( \text{Ba}^{2+} \) combines with \( \text{SO}_4^{2-} \) to form BaSO\(_4\), and \( \text{K}^+ \) combines with \( \text{Cl}^- \) to form KCl.
• This is a double displacement reaction.
• BaSO\(_4\) is insoluble in water and forms a white precipitate.
• This is also a precipitation reaction.

Step 4: Evaluate each option.

• (A) (i) is double displacement, (ii) is displacement reaction: Incorrect. Both are double displacement, and (ii) is not a displacement reaction.
• (B) Both are displacement reactions and precipitation reactions: Incorrect. They are double displacement, not simple displacement reactions.
• (C) Both are double displacement reactions and precipitation reactions: Correct. Both reactions involve exchange of ions and formation of precipitate.
• (D) (i) is displacement, (ii) is double displacement reaction: Incorrect. (i) is double displacement, not displacement.

Final Answer: (C) Both, (i) and (ii) are double displacement reactions and precipitation reactions.