Which of the following will show 'Tyndall effect'?

Which of the following are chemical changes?
$(a)$ Growth of a plant
$(b)$ Rusting of iron
$(c)$ Mixing of iron filings and sand
$(d)$ Cooking of food
$(e)$ Digestion of food
$(f)$ Freezing of water
$(g)$ Burning of a candle

Explain the following giving examples.
$(a)$ Colloid
$(b)$ Suspension

List the points of differences between homogeneous and heterogeneous mixtures.

How would you confirm that a colorless liquid given to you is pure water?

Name the technique used to separate:
$(i)$ Butter from curd,
$(ii)$ Salt from sea-water,
$(iii)$ Camphor from salt.