Physical and Chemical Changes — Question 2
Back to all questionsQuestion 2
State whether the following are physical or chemical changes.
(a) glowing of a bulb
(b) burning of sugar
(c) heating of water
(d) growing of a piglet into a pig
(e) burning of wood
(f) passing electric current through a heater's rod
(g) water cycle in nature
(h) respiration in living beings
(i) shaping a piece of glass
(j) lightning
(k) dissolving sugar in water
(l) heating a mixture of iron fillings and sulphur
(m) mixing oil with water
(n) cutting wood into small pieces
(o) photosynthesis
(p) Digestion of food
(q) Melting of wax
(r) Boiling of an egg
(s) Slaking of lime
(a) glowing of a bulb — Physical change
(b) burning of sugar — Chemical change
(c) heating of water — Physical change
(d) growing of a piglet into a pig — Chemical change
(e) burning of wood — Chemical change
(f) passing electric current through a heater's rod — Physical change
(g) water cycle in nature — Physical change
(h) respiration in living beings — Chemical change
(i) shaping a piece of glass — Physical change
(j) lightning — Chemical change
(k) dissolving sugar in water — Physical change
(l) heating a mixture of iron fillings and sulphur — Chemical change
(m) mixing oil with water — Physical change
(n) cutting wood into small pieces — Physical change
(o) photosynthesis — Chemical change
(p) Digestion of food — Chemical change
(q) Melting of wax — Physical change
(r) Boiling of an egg — Chemical change
(s) Slaking of lime — Chemical change
ICSE Class VII Chemistry Chapter 2 12 Marks
Physical and Chemical Changes — Quick Study Guide
Changes around us are classified as physical (no new substance formed) or chemical (new substance formed). Understanding the difference is fundamental to chemistry.
Key Definitions
- Physical change: No new substance formed, usually reversible (e.g., melting ice, dissolving sugar)
- Chemical change: New substance formed, usually irreversible (e.g., burning, rusting, cooking)
- Exothermic: Reaction that releases heat (e.g., burning fuel)
- Endothermic: Reaction that absorbs heat (e.g., photosynthesis)
Six Signs of Chemical Change
Colour change, gas evolution, temperature change, precipitate formation, smell change, light/sound emission.
Exam Tips
- Burning a candle = BOTH physical and chemical change
- Dissolving salt/sugar in water = physical change (recoverable)
- Not all physical changes are reversible (tearing paper)
- Learn the comparison table (6 differences) thoroughly
Bright Tutorials | ICSE Class VII Chemistry | Chapter 2: Physical and Chemical Changes | Contact: 9403781999