Science (086) — CBSE Class 10 board question

Nitric acid is a strong oxidising agent. When metals react with nitric acid, the hydrogen gas produced is immediately oxidised to water by the nitric acid itself. Instead of hydrogen, oxides of nitrogen (such as NO₂, NO) are evolved as by-products. Thus, hydrogen is generally not liberated in reactions of metals with nitric acid.

Source: Metals and Non-metals, Chapter 3

---

• The key reason is the oxidising nature of HNO₃ — examiners specifically look for this phrase.
• Mention that H₂ is oxidised to H₂O before it can escape, and that nitrogen oxides (NO₂ or NO) are released instead.
• This is a common 2-mark reason-based question; one clear explanation with the oxidising agent point scores full marks. Avoid writing a long paragraph — two to three crisp sentences are enough.