Which of the following statements are true for pure substances?
$(i)$ Pure substances contain only one kind of particles.
$(ii)$ Pure substances may be compounds or mixtures.
$(iii)$ Pure substances have the same composition throughout.
$(iv)$ Pure substances can be exemplified by all elements other than nickel.

On heating,calcium carbonate gets converted into calcium oxide and carbon dioxide.
$(a)$ Is this a physical or a chemical change?
$(b)$ Can you prepare one acidic and one basic solution by using the products formed in the above process? If so,write the chemical equations involved.

How will you separate a mixture of common salt,camphor,and iron filings? Describe the process.

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

$(a)$ 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.

Compare in tabular form the properties of true solution and colloids with respect to Tyndall effect and stability.