To make a saturated solution,$36 \,g$ of sodium chloride is dissolved in $100 \,g$ of water at $293 \,K$. Find its concentration at this temperature. (in $,\%$)

List the points of differences between homogeneous and heterogeneous mixtures.

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

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

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

How will you separate a mixture containing kerosene and petrol (difference in their boiling points is more than $25\,^{\circ}C$),which are miscible with each other?