According to Fajan's rules, which of the following conditions favors the formation of a covalent bond? MCQ with Answer and Explanation

Explanation:
A disproportionation reaction is a specific type of redox reaction where the same element in a single substance is simultaneously oxidized and reduced. In the decomposition of hydrogen peroxide (H2O2), oxygen has an oxidation state of -1. It is reduced to -2 in H2O and oxidized to 0 in O2.

Explanation:
Boiling water changes state from liquid to gas, but the chemical composition (H₂O) remains unchanged – physical change. Others form new substances.

Explanation:
Complete combustion of ethanol: C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + heat. In sufficient oxygen, carbon burns to CO₂, hydrogen to H₂O. Incomplete combustion (lack of O₂) produces CO and soot (C). Ethanol is a biofuel, reducing CO₂ emissions if derived from biomass. It has high octane number and is blended with petrol (gasohol). CO₂ is a greenhouse gas, but bioethanol is carbon-neutral over cycle.