Describe any three properties of colloids. Categorise the following examples of colloids into different categories of colloids: Jelly,fog,milk,shaving cream.

What volume of ethyl alcohol and water must be mixed together to prepare $250 \, mL$ of $50 \%$ by volume of alcohol in water?

What happens when a saturated solution is heated?

Pragya tested the solubility of four different substances at different temperatures and collected the data as given below (results are given in the following table,as grams of substance dissolved in $100 \,g$ of water to form a saturated solution).

Substance Dissolved	$283 \,K$	$293 \,K$	$313 \,K$	$333 \,K$	$353 \,K$
Potassium nitrate	$21$	$32$	$62$	$106$	$167$
Sodium chloride	$36$	$36$	$36$	$37$	$37$
Potassium chloride	$35$	$35$	$40$	$46$	$54$
Ammonium chloride	$24$	$37$	$41$	$55$	$66$

$(a)$ What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in $50 \,g$ of water at $313 \,K$?
$(b)$ Pragya makes a saturated solution of potassium chloride in water at $353 \,K$ and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.

Pragya tested the solubility of four different substances at different temperatures and collected the data as given below (results are given in the following table,as grams of substance dissolved in $100 \,g$ of water to form a saturated solution).

Substance Dissolved	$283 \,K$	$293 \,K$	$313 \,K$	$333 \,K$	$353 \,K$
Potassium nitrate	$21$	$32$	$62$	$106$	$167$
Sodium chloride	$36$	$36$	$36$	$37$	$37$
Potassium chloride	$35$	$35$	$40$	$46$	$54$
Ammonium chloride	$24$	$37$	$41$	$55$	$66$

$(a)$ Find the solubility of each salt at $293 \,K$. Which salt has the highest solubility at this temperature?
$(b)$ What is the effect of change of temperature on the solubility of a salt?

$A$ 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 $\%$)