Question

Which of the following substances enters our body when a red ant bites us?
A. Melittin
B. Calcium formate
C. Formic acid
D. Magnesium hydroxide

Answer 1

Hint: There are many types of ants out of which few are poisonous and their sting can be contagious. Red ants are one of the types whose sting can cause pain and redness, though it is very rare that red ant sting causes death.

Complete step by step answer:
Most ants spray or inject a venom, the main constituent of which is formic acid. The sting of an ant contains formic acid. When an ant bites it injects the acidic liquid into the skin. Formic acid is the common name for methanoic acid (HCOOH). It is injected as the chemical defence mechanism, ants contract their poison glands and the acid is released like a jet spring in the form of sting. Formic acid has a high ph and it can cause death.
It is a colorless fuming liquid that is miscible with water. It has a planar structure and consists of hydrogen bonded dimers. It is produced as a byproduct in the manufacturing of acetic acid, methanol combined with carbon monoxide in the presence of strong base such as sodium methoxide which forms methyl formate which on further hydrolysis produces methanoic acid or formic acid.

Hence the correct option is option C.

Note:
The effect of sting of an ant can be neutralized by rubbing with moist baking soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate. Since baking soda is alkaline in nature when it is rubbed on skin the formic acid reacts with baking soda forming salt and water which is a neutralization reaction.
The reaction is as follows,
$HCOOH + NaOH \to HCOONa + {H_2}O$.
Application of sodium hydroxide also neutralizes formic acid to form sodium methanoate and water.