Differentiate between an element and a compound. Categorize the following substances into elements and compounds: Sodium chloride,Iodine,Water,$24$ carat gold,Oxygen gas,Carbon.

Differentiate between an element and a compound (any two points). Give one example each.

Explain why particles of a colloidal solution do not settle down when left undisturbed,while in the case of a suspension they do.

$A$ solution contains $50 \, g$ of sugar in $350 \, g$ of water. Calculate the concentration of the solution in terms of mass by mass percentage of the solution. (in $\%$)

$A$ mixture containing two liquids visibly separated,is placed in a separating funnel. Answer the following:
$(i)$ What type of liquids form the mixture?
$(ii)$ Which of the liquids will form the lower layer?
$(iii)$ What is the principle behind this method of separation?

How can we obtain pure copper sulphate from an impure sample?