Observe the apparatus shown and answer the following questions:
$(a)$ Name the apparatus.
$(b)$ State one use of the apparatus.
$(c)$ State the principle involved in this process.

What are metalloids? Give examples.

Give an example each for the mixture having the following characteristics. Suggest a suitable method to separate the components of these mixtures:
$(a)$ $A$ volatile and a non-volatile component.
$(b)$ Two volatile components with appreciable difference in boiling points.
$(c)$ Two immiscible liquids.
$(d)$ One of the components changes directly from solid to gaseous state.
$(e)$ Two or more coloured constituents soluble in some solvent.

The teacher instructed three students $A$,$B$ and $C$ respectively to prepare a $50\%$ (mass by volume) solution of sodium hydroxide $(NaOH)$. $A$ dissolved $50\,g$ of $NaOH$ in $100\,mL$ of water,$B$ dissolved $50\,g$ of $NaOH$ in $100\,g$ of water while $C$ dissolved $50\,g$ of $NaOH$ in water to make $100\,mL$ of solution. Which one of them has made the desired solution and why?

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

Which of the following is a homogeneous mixture?