What is the name of the acid present in the sting of an ant that causes a burning sensation on the skin?

Introduction:
Everyday chemistry questions often ask about the acids and bases that occur in common plants, fruits, or insect stings. This question focuses on the acid present in the sting of an ant, which causes pain and irritation. Knowing such examples helps students connect chemistry with real life experiences.

Given Data / Assumptions:

• Ant stings cause a sharp burning sensation on the skin.
• This effect is due to the injection of a particular acid.
• The options list several familiar acids: acetic, citric, formic, lactic, and oxalic.
• We assume the question refers to common red or black ants that people usually encounter.

Concept / Approach:
The chemical responsible for the pain and irritation in most ant stings is formic acid. The name formic comes from the Latin word for ant. When an ant stings, it injects a small amount of formic acid into the skin, which leads to a burning feeling and sometimes redness or swelling. Other acids such as acetic acid in vinegar, citric acid in citrus fruits, and lactic acid in sour milk have different common sources.

Step-by-Step Solution:
Step 1: Recall the association between ant stings and formic acid from school level chemistry examples.Step 2: Note that the root word form is related to ants, which reinforces the link.Step 3: Compare with acetic acid, which is the main acid in vinegar, and citric acid, which is found in lemons and oranges.Step 4: Lactic acid forms in muscles during heavy exercise and in curd, and oxalic acid is present in some leafy vegetables.Step 5: Based on this, identify formic acid as the acid present in ant sting.

Verification / Alternative check:
Many textbooks state that mild ant stings can be neutralised by rubbing a weak base such as baking soda solution on the affected area. This is because an acid causes the pain, and a base can neutralise it. When describing this example, they specifically name formic acid as the substance injected by ants, which confirms the correct answer.

Why Other Options Are Wrong:
Acetic acid is associated with vinegar and does not come from ant stings. Citric acid gives the sour taste of citrus fruits such as lemon and orange. Lactic acid is produced in muscles during intense exercise and is present in curd and some fermented foods. Oxalic acid occurs in spinach and some other plants and is not the acid used by ants for defence.

Common Pitfalls:
Students sometimes get confused between different common acids and may guess citric or acetic acid because these names are more familiar. The key memory aid is that formic acid was first isolated from ants and was named directly after them. Remembering that link makes this question straightforward in exams.

Final Answer:
Correct option: Formic acid