Which one among the following statements is not correct?

The reaction of methane and chlorine in the presence of sunlight is a photochemical substitution reaction [1]. In this process, chlorine radicals replace hydrogen atoms in methane one by one, producing chloromethane (CH3Cl) and hydrogen chloride (HCl) as the primary byproduct, not hydrogen gas (H2). Palladium (Pd) acts as a catalyst for the addition of hydrogen to alkenes, converting them into saturated alkanes. Ethanol undergoes complete combustion in oxygen to produce carbon dioxide, water, heat, and light [1]. Saturated hydrocarbons typically burn with a clean blue flame, whereas unsaturated hydrocarbons, due to their higher carbon content, often undergo incomplete combustion and burn with a yellow, sooty flame [2]. Therefore, statement 1 is incorrect because the byproduct of methane chlorination is HCl, not H2.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.3.4 Substitution Reaction > p. 71
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Activity 4.4 > p. 69