Yes iodoform test is not given by acetic acid because this test shows only the presence of methyl ketone so only aldehyde, ketone and alcohol show positive response towards iodoform test.

**Iodoform Test and Acetic Acid**

**Introduction**
The iodoform test is a chemical test used to detect the presence of compounds that contain the CH3CO group, also known as the acetyl group. However, acetic acid itself does not give a positive iodoform test. This test is commonly used to identify compounds such as alcohols and ketones.

**Explanation**
The iodoform test is based on the reaction of compounds containing the CH3CO group with iodine and a strong base, such as sodium hydroxide (NaOH). In this test, the acetyl group is oxidized by iodine, resulting in the formation of iodoform (CHI3) and sodium acetate (CH3COONa).

The reaction can be represented as follows:
CH3COCH3 + 4I2 + 6NaOH → CHI3 + 5NaI + CH3COONa + 3H2O

**Mechanism**
During the iodoform test, the base deprotonates the hydroxyl group of the acetyl compound, creating a reactive intermediate. This intermediate then undergoes oxidation by iodine, resulting in the formation of iodoform.

**Why Acetic Acid Does Not Give a Positive Iodoform Test?**
Acetic acid (CH3COOH) does not contain a carbonyl group (C=O) that is necessary for the iodoform test to occur. In the iodoform test, the carbonyl group is oxidized, leading to the formation of iodoform. Acetic acid lacks this carbonyl group and therefore cannot react with iodine to produce iodoform.

**Conclusion**
In conclusion, acetic acid does not give a positive iodoform test because it does not contain a carbonyl group necessary for the reaction to occur. The iodoform test is specific to compounds that contain the CH3CO group, such as alcohols and ketones. By performing the iodoform test, we can identify the presence of these compounds and distinguish them from other organic compounds.