You are provided with a solution of substance $'X'$. How will you test whether it is saturated or unsaturated with respect to $'X'$ at a given temperature? What happens when a hot saturated solution is allowed to cool?

$(a)$ Calculate the mass of potassium chloride required to prepare its $40 \%$ solution in $100 \, g$ of water.
$(b)$ Explain the term solubility and the effect of temperature on it.

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?

$A$ mixture of sulphur and carbon disulphide is

"Tyndall Effect can be observed when sunlight passes through the canopy of dense forest." Explain how this occurs.

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.