State four differences between physical and chemical changes.

What do you observe when:

(a) Water is boiled

(b) a piece of paper is burnt

(c) some ice cubes are kept in a glass tumbler

(d) solid ammonium chloride is heated

(e) an iron nail is kept in tap water for few days

(f) a spoon of sugar is heated in a pan

(g) a lighted match stick is brought near the mouth of the test tube containing hydrogen gas

(h) quick lime is dissolved in water

(i) little amount of curd is added to a bowl containing warm milk and kept for five hours?

Fill in the blanks

(a) A new substance is always formed in a …………… change.

(b) Melting of ice is a …………… change.

(c) When a candle burns, wax melts. Melting of wax is a …………… change.

(d) Chemical change occurs as a result of …………… between two substances.

(e) Burning of a fuel is a …………… change.

(f) Revolution of the earth around the sun is a …………… change.

(g) Growing of a seedling into a plant is a …………… change.

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