Which of the following is a homogeneous mixture?

When is a solution said to be saturated? How can you change an unsaturated solution to a saturated solution without adding any more solute to it?

What is tincture of iodine? Identify the solute and solvent in 'tincture of iodine.' Why is the Tyndall effect not seen in a true solution?

$A$ 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?

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?

Identify the solute and the solvent for the following mixtures:
$(a)$ Tincture of iodine
$(b)$ Soda water
$(c)$ Sugar solution
$(d)$ Polluted air
$(e)$ Dilute hydrochloric acid