How can a colloidal solution of arsenious sulphide be prepared?

Various types of colloids are given below. Match Column $X$ with Column $Y$.

$X$ (Colloid)	$Y$ (Classification)
$I$. Smoke	$A$. Sol
$II$. Gelatin	$B$. Aerosol
$III$. Soap lather	$C$. Emulsion
$IV$. Milk	$D$. Foam

Which of the following terms is not related with colloids?

At the critical micelle concentration $(CMC)$ the surfactant molecules

$A$ colloidal system consisting of a gas dispersed in a solid is called a/an:

In which of the following,the sol is not correctly matched with respect to its charge?
$I$. $Al_2O_3 \cdot xH_2O$ sol; $+ve$ sol
$II$. Starch sol; $+ve$ sol
$III$. $TiO_2$ sol; $-ve$ sol
$IV$. Methylene blue sol; $+ve$ sol
The correct answer is