Why is the path of light not visible in a solution when a beam of light is passed through it?

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

The substances that sublime easily are

Compare in tabular form the properties of true solution and colloids with respect to Tyndall effect and stability.

Classify the substances given in the figure into elements and compounds.

Classify each of the following as a physical or a chemical change. Give reasons.
$(a)$ Drying of a shirt in the sun.
$(b)$ Rising of hot air over a radiator.
$(c)$ Burning of kerosene in a lantern.
$(d)$ Change in the colour of black tea on adding lemon juice to it.
$(e)$ Churning of milk cream to get butter.