Which one among the following is present in the nettle leaf hairs that causes burning pain ?

The burning sensation and pain caused by touching nettle leaf hairs are due to the injection of methanoic acid (commonly known as formic acid) into the skin. Nettle plants (Urtica dioica) are equipped with stinging hairs called trichomes that function like tiny hypodermic needles.

• Mechanism: When these brittle hairs are touched, their tips break off, allowing them to penetrate the skin and release a cocktail of chemicals, primarily methanoic acid, which causes immediate irritation and inflammation.
• Chemical Nature: Methanoic acid (HCOOH) is the simplest carboxylic acid. While the sting also contains other substances like histamine and serotonin, methanoic acid is the specific acidic component responsible for the characteristic "burn."
• Neutralization: As per NCERT Science textbooks, the acidic nature of the sting can be neutralized by rubbing the affected area with the leaf of a dock plant, which typically grows near nettles and contains alkaline juices.