**(A):** The oxidation number of in is 0. <br> **(R):** Formaldehyde contains a carbonyl group. — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

**Assertion:** Calculation: $x + 2(+1) + 1(-2) = 0 \Rightarrow x = 0$. Statement is true. <br>**Reason:** Formaldehyde ($H_2C=O$) does contain a carbonyl group. However, many compounds with carbonyl groups have carbon in different oxidation states (e.g., $CO_2$ is +4, $CH_3CHO$ is -1 and +1). The O.S. is 0 due to the specific balance of $H$ and $O$ atoms.