Which one of the following shows that iodoform test for a compound is positive?

Explanation

The positive result of the iodoform test is indicated by the formation of yellow crystals. These crystals are iodoform (CHI₃), a pale yellow solid with a characteristic medicinal odor. Here's a breakdown:Iodoform Test: This test is used to detect the presence of a carbonyl group (C=O) with a methyl group directly attached to it (CH₃CO-) or an alcohol that can be oxidized to such a carbonyl group (CH₃CH(OH)-). Positive Result: When iodine (I₂) and a base (such as NaOH) are added to a compound containing these groups, a reaction occurs that produces iodoform (CHI₃). This iodoform precipitates out of the solution as distinct yellow crystals. The other options are incorrect:Formation of carboxylate salt: This is a general characteristic of carboxylic acids reacting with bases, but not specific to the iodoform test.Brick red precipitate formation: This is characteristic of Fehling's test, which is used to detect aldehydes.Formation of water: Water is often a byproduct of many organic reactions, but its formation is not the indicator of a positive iodoform test.Therefore, the correct answer is Yellow crystals.