Question

single replacement, double replacement, synthesis, zn + h₂s → h₂ + zns (zinc displaces hydrogen), 2h₂ + o₂ → 2h₂o, 2h₂o (water) → 2h₂ (hydrogen) + o₂ (oxygen), ch₄ + 2o₂ → co₂ + 2h₂o

Explanation:

Step1: Identify the reaction type for \( \text{CH}_4 + 2\text{O}_2

ightarrow \text{CO}_2 + 2\text{H}_2\text{O} \)
Combustion reactions involve a fuel (like \( \text{CH}_4 \), methane) reacting with oxygen (\( \text{O}_2 \)) to produce carbon dioxide (\( \text{CO}_2 \)) and water (\( \text{H}_2\text{O} \)), often with heat/light. This reaction fits that pattern.

Step2: Locate the "Combustion" label

Looking at the grid, the bottom - middle cell is labeled "Combustion". The reaction \( \text{CH}_4 + 2\text{O}_2
ightarrow \text{CO}_2 + 2\text{H}_2\text{O} \) is a combustion reaction, so it should be placed in the "Combustion" cell.

Answer:

The reaction \( \text{CH}_4 + 2\text{O}_2
ightarrow \text{CO}_2 + 2\text{H}_2\text{O} \) belongs in the "Combustion" cell (the bottom - middle cell in the grid).