Which of the following is incorrect?

• A

  Primary alcohols are very easily oxidised to aldehydes, which are oxidised to acids with same number of C-atoms.
• Correct answer
  B

  Secondary alcohols are very easily oxidised to ketones, which are oxidised to acids with same number of C-atoms.
• C

  Secondary alcohols are easily oxidised to ketones, which are oxidised to acids with lesser number of C-atoms.
• D

  Secondary and tertiary alcohols on oxidation form acids with lesser number of C-atoms.

Solution

Primary alcohols are easily oxidised to aldehydes and then to acid, both containing the same number of carbon atoms, while secondary alcohols are easily oxidised to ketones with same number of carbon atoms, but ketone oxidised to carboxylic acid containing lesser number of carbon atoms than original alcohol.
Thus all alcohols on oxidation finally give acids but acids obtained from $2^{\circ}$ and $3^{\circ}$ alcohols contain less C-atom.

Hence, the correct answer is option: 'B'.