Question 30
Which among the following are physical or chemical changes?
(a) Evaporation of petrol.
(b) Burning of Liquefied Petroleum Gas (LPG).
(c) Heating of an iron rod to red hot.
(d) Curdling of milk.
(e) Sublimation of solid ammonium chloride.
The physical changes involve change in the physical properties of a substance. The chemical changes involve change in the chemical properties of a substance.
(a), (c) and (e) — are physical changes.
(b) and (d) are chemical changes.