Question

which of the following is a double replacement reaction?

\\(\text{c}_3\text{h}_8 + 5\text{o}_2 \
ightarrow 3\text{co}_2 + 4\text{h}_2\text{o}\\)

\\(2\text{ag} + \text{h}_2\text{s} \
ightarrow \text{ag}_2\text{s} + \text{h}_2\\)

\\(2\text{ki} + \text{pb}(\text{no}_3)_2 \
ightarrow 2\text{kno}_3 + \text{pbi}_2\\)

Explanation:

Analyze the first reaction

The reaction \(\text{C}_3\text{H}_8 + 5\text{O}_2
ightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}\) represents a hydrocarbon reacting with oxygen to produce carbon dioxide and water, which is a combustion reaction.

Analyze the second reaction

The reaction \(2\text{Ag} + \text{H}_2\text{S}
ightarrow \text{Ag}_2\text{S} + \text{H}_2\) involves a single element (\(\text{Ag}\)) replacing another element (\(\text{H}\)) in a compound, which is a single replacement reaction.

Analyze the third reaction

The reaction \(2\text{KI} + \text{Pb(NO}_3)_2
ightarrow 2\text{KNO}_3 + \text{PbI}_2\) involves two ionic compounds exchanging ions to form two new compounds, which is a double replacement reaction.

Answer:

• (A) \(\text{C}_3\text{H}_8 + 5\text{O}_2

ightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}\)

• (B) \(2\text{Ag} + \text{H}_2\text{S}

ightarrow \text{Ag}_2\text{S} + \text{H}_2\)

• **(C) \(2\text{KI} + \text{Pb(NO}_3)_2

ightarrow 2\text{KNO}_3 + \text{PbI}_2\) (Correct answer)**