Consider the following reaction equation: CaO + SiO$_{2}$ ------> CaSiO$_{3}$ Silicon(IV) oxide is acting as

Step 1: Analyze the question CaO reacts with SiO₂ to form CaSiO₃ (calcium silicate, a salt). We need to say what role SiO₂ plays.

Step 2: Concept

• A basic oxide is a metal oxide that reacts with acids to form salt (and water).
• An acidic oxide is usually a non-metal oxide that reacts with bases or basic oxides to form a salt.
• Oxidizing and reducing agents are defined by electron transfer, meaning a change in oxidation number.

Step 3: Solution Check the oxidation numbers:

• CaO: Ca = +2, O = -2
• SiO₂: Si = +4, O = -2
• CaSiO₃: Ca = +2, Si = +4, O = -2

No element changes its oxidation number, so this is not a redox reaction. That rules out B and D (oxidizing and reducing agents).

The reaction is a combination of a basic oxide (CaO, a metal oxide) with an oxide of a non-metal (SiO₂) to form a salt:

CaO (basic oxide) + SiO₂ (acidic oxide) → CaSiO₃ (salt)

So SiO₂ is behaving as an acidic oxide, reacting with the basic oxide CaO. This is the same principle used in the blast furnace, where limestone (CaO) removes silica impurities as slag (CaSiO₃).

Step 4: Answer SiO₂ is acting as an acidic oxide, which is option C.

Tip: When two oxides combine into a salt, one is acidic and the other basic. Metal oxide = basic (CaO), non-metal oxide = acidic (SiO₂). Always check oxidation numbers first. If none change, it is not a redox reaction, so you can eliminate the "oxidizing agent" and "reducing agent" options immediately.