Ethanol is oxidised to ethanoic acid. Taking oxidation numbers by the usual rules ( $H$ is $+ 1$ , $O$ is $- 2$ ), the oxidation number of the carbinol carbon (the carbon bonded to oxygen) changes by

Answer: D

CH X_{3} - CH X_{2} - OH

the carbinol carbon has two

H

(

- 2

in total), one

O

(

+ 1

) and one

C

(0): oxidation number

- 1

. In the carboxyl carbon of

CH X_{3} - COOH

O

O

and

C

give

+ 1

+ 1

+ 1

= + 3

. The change is

+ 3 - (- 1) = + 4