Let's carefully analyze the information given in the question to correctly fill in the gaps.
1. The first part of the question states: "Limestone is heated to produce [tex]$\qquad$[/tex] 1. [tex]$\qquad$[/tex] and carbon dioxide."
- When limestone (which is primarily composed of calcium carbonate, [tex]\( \text{CaCO}_3 \)[/tex]) is heated, it undergoes a chemical reaction. This reaction decomposes calcium carbonate into calcium oxide ([tex]\( \text{CaO} \)[/tex]) and carbon dioxide ([tex]\( \text{CO}_2 \)[/tex]). The substance produced here, calcium oxide, is commonly known as lime.
2. The second part of the question states: "This reaction is called [tex]$\qquad$[/tex] 2. [tex]$\qquad$[/tex]"
- The reaction in which a compound breaks down when heated is known as thermal decomposition. So, heating limestone to form lime and carbon dioxide is an example of thermal decomposition.
Given these explanations, let's review the multiple-choice options provided:
\begin{tabular}{|c|c|c|}
\hline & 1 & 2 \\
\hline A & lime & neutralisation \\
B & lime & thermal decomposition \\
C & slaked lime & neutralisation \\
D & slaked lime & thermal decomposition \\
\hline
\end{tabular}
- Option A: "lime" is correct for gap 1, but "neutralisation" for gap 2 is incorrect.
- Option B: "lime" is correct for gap 1, and "thermal decomposition" for gap 2 is correct.
- Option C: "slaked lime" is incorrect for gap 1, and "neutralisation" for gap 2 is incorrect.
- Option D: "slaked lime" is incorrect for gap 1, but "thermal decomposition" for gap 2 is correct.
Based on the correct word matches:
- Gap 1 should be "lime".
- Gap 2 should be "thermal decomposition".
Therefore, the correct answer is Option B, completing the gaps as follows:
\begin{tabular}{|c|c|c|}
\hline & 1 & 2 \\
\hline B & lime & thermal decomposition \\
\hline
\end{tabular}
