To solve the problem, we need to evaluate each of the statements and options given:
- Statement (A): \(\text{NaOCl}\) when reacted with \(\text{KI}\) gives \(\text{KOI}\).
- Sodium hypochlorite (\(\text{NaOCl}\)) and potassium iodide (\(\text{KI}\)) actually react to produce iodine, not potassium hypoiodite (\(\text{KOI}\)). Therefore, statement (A) is incorrect.
- Statement (B): \(\text{KOI}\) is the best reducing agent.
- Potassium hypoiodite (\(\text{KOI}\)) is not commonly considered the most effective reducing agent. Other compounds are much more recognized for this property. Therefore, statement (B) is incorrect.
- Statement (C): Methanoic acid gives an iodoform test.
- The iodoform test is given by compounds containing a methyl ketone group (\(\text{CH}_3\text{CO}-\)) or related alcohols, after their oxidation. Methanoic acid does not contain a methyl ketone group and thus does not give the iodoform test. Therefore, statement (C) is incorrect.
- Statement (D): Isopropyl alcohol gives the iodoform test.
- Isopropyl alcohol (\(\text{CH}_3\text{CH(OH)CH}_3\)) can be oxidized to a methyl ketone, which reacts positively in the iodoform test Producing a yellow precipitate of iodoform. Therefore, statement (D) is correct.
- Statement (E): \(\text{H}_3\text{C}–\text{CH}=\text{CH}–\text{CO}–\text{CH}_3\) gives the iodoform test.
- This compound contains a methyl ketone group, allowing it to undergo the iodoform reaction, which makes statement (E) correct.
After evaluating each statement, the correct options that hold true are D and E only. Therefore, the correct answer is
D, E only
.