Salt can be recovered from its solution by evaporation. Can you suggest any other technique also?

Smoke and fog both are aerosols. In what way are they different?

$(i)$ Name the compound formed on heating a mixture of iron filings and sulphur.
$(ii)$ If dilute $HCl$ is added to the above compound,name the gas evolved and write down its two properties.

Which of the following will show Tyndall effect? Why?
$(a)$ Salt solution
$(b)$ Milk
$(c)$ Copper sulphate solution
$(d)$ Starch solution.

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?

Elements are classified as metals,non-metals,and metalloids. Give any one property of each. Also,give one example of each.