Here's the chemical equation:

2 H₂ (g) + O₂ (g) → 2 H₂O (g) + heat

Explanation:

* H₂ (g) represents hydrogen gas.

* O₂ (g) represents oxygen gas.

* H₂O (g) represents water vapor.

* heat is released, indicating an exothermic reaction.

What happens:

* When hydrogen gas is exposed to a source of ignition (like a flame), it reacts with oxygen in the air.

* This reaction combines two hydrogen molecules (H₂) with one oxygen molecule (O₂) to form two water molecules (H₂O).

* This process releases a significant amount of heat and light, which is what we observe as the flame of burning hydrogen.

Key points:

* Hydrogen combustion is a very efficient reaction, producing a lot of energy per unit mass of fuel.

* It is a clean-burning fuel, producing only water as a by-product, making it a promising alternative to fossil fuels.

* However, handling and storing hydrogen gas requires special precautions due to its highly flammable nature.