On burning hydrogen in air, the colour of flame is — Hydrogen Chemistry Question

💡 Solution & Explanation

I don't see the options (A, B, C, D) provided in your question. However, I can explain what happens when hydrogen burns in air: **When hydrogen burns in air:** $$2H_2 + O_2 \rightarrow 2H_2O$$ The flame is **pale blue** (or colorless to very pale blue). **Why this color?** - Hydrogen combustion is a clean, high-temperature reaction (~2800 K) - The flame color arises from excited water molecules and a small amount of blue emission from the combustion process - There are no colored ions or species like in metal combustion (which produce yellow, red, green flames) **Note:** In pure oxygen, the flame is nearly **invisible/colorless** because the reaction is extremely hot but produces only water vapor. In air (with nitrogen present), you see a **pale blue flame** due to slight thermal radiation and molecular excitation. If option B in your question is "pale blue," that's correct. If it's "colorless," that's also acceptable depending on the context (air vs. pure oxygen). Could you share the options so I can confirm which answer B refers to?