$A$ sample of water under study was found to boil at $102\,^{\circ}C$ at normal temperature and pressure. Is the water pure? Will this water freeze at $0\,^{\circ}C$? Comment.

Explain the following giving examples:
$(a)$ Saturated solution
$(b)$ Pure substance

$(a)$ $7\, g$ of iron filings and $4\, g$ of sulphur powder is treated with dilute sulphuric acid at room temperature. Name the gas produced.
$(b)$ The same mixture is heated strongly,cooled and then treated with dilute sulphuric acid. Which gas would be produced?
$(c)$ What is the cause of this difference in results of chemical reaction in different conditions?

$(a)$ Name the separation techniques which you will apply for the separation of the following mixtures:
$(i)$ Small pieces of metal in the engine oil of a car.
$(ii)$ Fine mud particles suspended in water.
$(iii)$ Oil from water.
$(iv)$ Sodium chloride from its solution in water.
$(v)$ Camphor from salt.
$(vi)$ Wheat grains from husk.
$(b)$ Classify the following as a chemical or physical change:
$(i)$ Water boils to form steam.
$(ii)$ Burning of paper.
$(iii)$ An almirah gets rusted.
$(iv)$ Making a fruit salad with raw fruits.

How will you separate a mixture of common salt $(A)$,camphor $(B)$ and iron filings $(C)$? Describe the process.

The 'sea-water' can be classified as a homogeneous as well as heterogeneous mixture. Comment.