Which one of the following is a chemical change ?
Cutting of hair
Graying of hair naturally
Swelling of resin in water
Cutting of fruit
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-2 – 2017
A) Cutting of hair is a physical change; the hair material itself (keratin) remains chemically unchanged, only its physical shape and size are altered.
B) Graying of hair naturally involves chemical changes in the hair follicle where the production of melanin (the pigment that gives hair its color) decreases or stops. This is a biological process that alters the chemical composition of the hair shaft over time, leading to a change in color. It is an irreversible change at the level of pigment production.
C) Swelling of resin in water is a physical change; the resin absorbs water but its chemical composition does not fundamentally change. This is often a process of hydration or dissolution/dispersion.
D) Cutting of fruit is primarily a physical change; the fruit’s chemical composition remains the same, although the exposed surface might subsequently undergo chemical reactions like oxidation (browning), but the act of cutting is physical.
Therefore, graying of hair is a chemical change.
– Physical change alters form or appearance without changing chemical composition.
– Graying of hair involves a change in pigment (melanin) production, a chemical/biological process.