Why is the interconversion of states of matter considered a physical change? Give three reasons to justify your answer.

$A$ 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 $\%$)

$(a)$ Give any one point of difference between true solution,colloidal solution,and suspension.
$(b)$ $20 \, g$ of sodium chloride is dissolved in $100 \, mL$ of water. How will you test whether the given solution is saturated or unsaturated at the given temperature?
$(c)$ Suggest any one method by which we can increase the solubility of saturated solutions.

What would you observe when:
$(a)$ a saturated solution of potassium chloride prepared at $60^{\circ} C$ is allowed to cool at room temperature?
$(b)$ an aqueous sugar solution is heated to dryness?
$(c)$ a mixture of iron filings and sulphur powder is heated strongly?

Write your observations when the following processes take place:
$(a)$ An aqueous solution of sugar is heated to dryness.
$(b)$ $A$ saturated solution of potassium chloride prepared at $60^\circ C$ is allowed to cool at room temperature.
$(c)$ $A$ mixture of iron filings and sulphur powder is heated strongly.
$(d)$ $A$ beam of light is passed through a colloidal solution.
$(e)$ $Dil. HCl$ is added to the mixture of iron and sulphur.

Two chemical species $X$ and $Y$ combine together to form a product $P$ which contains both $X$ and $Y$.
$X + Y \to P$
$X$ and $Y$ cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species $X$,$Y$ and $P$ are correct?
$(i)$ $P$ is a compound
$(ii)$ $X$ and $Y$ are compounds
$(iii)$ $X$ and $Y$ are elements
$(iv)$ $P$ has a fixed composition