Which one of the following sols acts as a lyophilic colloid?

When the dispersion medium is water,the colloidal system is called:

Which of the following colloidal systems represents a sol?

$A$ coagulating agent frequently added to water to remove the suspended and colloidal impurities is

Which statement is correct regarding a gel?

The flocculation value of $HCl$ for arsenic sulphide sol is $30 \; mmol \; L^{-1}$. If $H_{2}SO_{4}$ is used for the flocculation of arsenic sulphide,the amount,in grams,of $H_{2}SO_{4}$ in $250 \; mL$ required for the above purpose is (molecular mass of $H_{2}SO_{4} = 98 \; g/mol$)