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

$(a)$ Calculate the mass of potassium chloride required to prepare its $40 \%$ solution in $100 \, g$ of water.
$(b)$ Explain the term solubility and the effect of temperature on it.

Write your observations when the following processes take place:
$(a)$ An aqueous solution of sugar is heated to dryness.
$(b)$ $A$ saturated solution of potassium chloride prepared at $60^\circ C$ is allowed to cool at room temperature.
$(c)$ $A$ mixture of iron filings and sulphur powder is heated strongly.
$(d)$ $A$ beam of light is passed through a colloidal solution.
$(e)$ $Dil. HCl$ is added to the mixture of iron and sulphur.

You are provided with a mixture containing sand, iron filings, ammonium chloride, and sodium chloride. Describe the procedures you would use to separate these constituents from the mixture.

Which of the following are not compounds?
$(a)$ Chlorine gas
$(b)$ Potassium chloride
$(c)$ Iron
$(d)$ Iron sulphide
$(e)$ Aluminium
$(f)$ Iodine
$(g)$ Carbon
$(h)$ Carbon monoxide
$(i)$ Sulphur powder

Define distillation.