Which of the following are physical changes?
$(i)$ Melting of iron metal
$(ii)$ Rusting of iron
$(iii)$ Bending of an iron rod
$(iv)$ Drawing a wire of iron metal

What are metalloids? Give examples.

Which of the following is a compound?

Classify each of the following as a physical or a chemical change. Give reasons.
$(a)$ Drying of a shirt in the sun.
$(b)$ Rising of hot air over a radiator.
$(c)$ Burning of kerosene in a lantern.
$(d)$ Change in the colour of black tea on adding lemon juice to it.
$(e)$ Churning of milk cream to get butter.

$(a)$ Illustrate with an example that physical and chemical changes can take place together.
$(b)$ Which of the following are chemical changes?
$(i)$ Mixing of iron filings and sand
$(ii)$ Growth of plant
$(iii)$ Rusting of iron
$(iv)$ Freezing of water

Classify the following as physical or chemical properties:
$(a)$ The composition of a sample of steel is: $98\%$ iron,$1.5\%$ carbon,and $0.5\%$ other elements.
$(b)$ Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
$(c)$ Metallic sodium is soft enough to be cut with a knife.
$(d)$ Most metal oxides form alkalis on interacting with water.