Answer: (3)
Iodoform test is used to check the presence of carbonyl compounds with the structure R-CO-CH3 or alcohols with the structure R-CH(OH)-CH3 in a given unknown substance. When Iodine and sodium hydroxide are added to a compound that contains secondary alcohol with a methyl group in the alpha position, a pale yellow precipitate of iodoform or triiodomethane is formed. However, methanol does not react positively to the Iodoform test due to the absence of an alpha-methyl group.