Chemistry
Give reasons:
Freezing of water to ice and evaporation of water are physical changes.
Answer
Freezing of water to ice and evaporation of water are physical changes because the changes are reversible and the chemical composition of the substance remains the same. No new substance if formed. Only change of state occurs i.e. water (liquid) is converted to ice (solid) in freezing and in evaporation, water (liquid) is changed to vapour (gaseous) state.
Related Questions
Why is burning of a candle an example of both a physical and a chemical change ?
Give four differences between physical and chemical changes.
Name the terms marked as A, B, C, D and E in the following and state the type of changes.
In which of the above changes does a gain in mass take place?
During a power cut, Vihaan's mother lit a candle. Vihaan observed that :
- The solid wax near the flame melted and later resolidified, when it dripped onto the table.
- The molten wax at the wick burnt with a flame, producing light, smoke and heat.
Answer the following questions :
(a) Classify the changes below as physical or chemical with justification :
(i) Solid wax melting and resolidifying.
(ii) Molten wax at the wick burning to produce light, heat and smoke.
(b) Name the gases produced when molten wax is burnt.
(c) Burning of wax is an exothermic reaction releasing energy in the form of heat and light. Can you think of an exothermic reaction occurring in living beings?