Question

Observe the given Venn diagram carefully and fill in the blanks by choosing an appropriate option.

• A. $1$ - Falling of trees, $2$ - Occurrence of rainbow, $3$ - Growth of plants, $4$ - Tearing paper into pieces
• B. $1$ - Knitting sweater from wool, $2$ - Setting of milk to form curd, $3$ - Making rice puddings, $4$ - Dissolving sugar in water
• C. $1$ - Expansion of mercury in thermometer, $2$ - Breaking of glass, $3$ - Lighting LPG stove, $4$ - Boiling an egg
• D. $1$ - Filling a water bottle, $2$ - Melting of ice, $3$ - Burning of paper, $4$ - Boiling of water

Answer 1

Answer: (C)

$1$ - Expansion of mercury in thermometer, $2$ - Breaking of glass, $3$ - Lighting LPG stove, $4$ - Boiling an egg

$1$. Expansion of mercury in the thermometer is a physical change which is reversible as mercury returns to its original position (contracts) on cooling.

$2$. Breaking of glass is a physical change which is irreversible as broken pieces of glass cannot be joined back.

$3$. Lighting LPG stove involves both physical and chemical changes. When LPG comes out of the cylinder it changes from liquid to gaseous state which is a physical change. Then the gas burns in the air which is a chemical change.

$4$. Boiling of an egg is a chemical change, liquid egg converts to solid egg having different texture and taste which is irreversible as a boiled egg cannot be changed into original liquid form.