You are provided with a fine white-coloured powder which is either sugar or salt. How would you identify it without tasting?

Three students $A, B$ and $C$ prepared mixtures using chalk powder,common salt and milk respectively in water. Whose mixture
$(i)$ would not leave residue on filter paper after filtration?
$(ii)$ would show Tyndall effect?
$(iii)$ would give transparent/clear solution?
$(iv)$ would settle down at the bottom when left undisturbed?
$(v)$ could be filtered by filter paper?

Try segregating the things around you as pure substances or mixtures.

$(a)$ Write any three points of differences between homogeneous and heterogeneous mixtures.
$(b)$ Give two reasons for supporting that water is a compound and not a mixture.

$(a)$ $7\, g$ 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?

Classify each of the following as an element,compound,or mixture:
Gold,Air,Marble,Milk,Sugar.