Final answer:
The combination reaction among the given options is 2SO₂ + O₂ → 2SO₃, as it is the only reaction where two reactants combine to form a single product. The correct option is a.
Step-by-step explanation:
To determine which of the given reactions is a combination reaction, we must identify the reaction in which two or more substances combine to form a single product. Let's analyze each one:
- a. 2SO₂ + O₂ → 2SO₃ - This reaction features two reactants combining to form a single product, sulfur trioxide (SO₃), and is an example of a combination reaction.
- b. 2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O - This is a combustion reaction where acetylene (C₂H₂) burns in the presence of oxygen to form carbon dioxide and water.
- c. 2H₂O₂ → 2H₂O + O₂ - This reaction is a decomposition reaction because hydrogen peroxide (H₂O₂) decomposes into water and oxygen gas.
- d. AgNO₃ + NaCl → AgCl + NaNO₃ - This is an example of a double displacement reaction, where ions in two compounds exchange partners.
From these options, the answer is a. 2SO₂ + O₂ → 2SO₃, as it is the only combination reaction according to the definition.