Arun has prepared a $0.01\%$ (by mass) solution of sodium chloride in water. Which of the following correctly represents the composition of the solution?

Colloidal solution appears to be homogeneous but actually it is heterogeneous. Give justification for this statement.

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

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?

$A$ group of students took an old shoe box and covered it with black paper from all sides. They fixed a source of light (a torch) at one end of the box by making a hole in it and made another hole on the other side to view the light. They placed a milk sample contained in a beaker/tumbler in the box as shown in the figure. They were amazed to see that the milk taken in the tumbler was illuminated. They tried the same activity by taking a salt solution but found that light simply passed through it.
$(a)$ Explain why the milk sample was illuminated. Name the phenomenon involved.
$(b)$ Same results were not observed with a salt solution. Explain.
$(c)$ Can you suggest two more solutions which would show the same effect as shown by the milk solution?

Write the steps you would use for making tea. Use the words solution,solvent,solute,dissolve,soluble,insoluble,filtrate and residue.