An alcohol on oxidation first yield aldehyde which on further oxidation yield carboxylic acid, both containing same number of carbon atoms as the alcohol, the alcohol is

The oxidation of alcohols is a stepwise process determined by the degree of the alcohol. Primary alcohols undergo oxidation to first form aldehydes, which are then further oxidized to carboxylic acids [3]. Crucially, in this sequence, the carbon skeleton remains intact, meaning the resulting aldehyde and carboxylic acid contain the same number of carbon atoms as the parent alcohol [2]. For example, ethanol (2 carbons) oxidizes to ethanal and then to ethanoic acid [1]. In contrast, secondary alcohols oxidize to ketones, which are resistant to further oxidation under normal conditions and would require carbon-carbon bond cleavage to form acids with fewer carbons. Tertiary alcohols do not easily oxidize because they lack a hydrogen atom on the carbon bearing the hydroxyl group. Therefore, only a primary alcohol satisfies the condition of yielding an aldehyde and then a carboxylic acid with the same carbon count.

Sources

1. [3] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Formation of coal and petroleum > p. 71
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Table 4.4 Nomenclature of organic compounds > p. 68
3. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > What you have learnt > p. 77