The charge of $SnO_2$-sol in alkaline and acidic medium are respectively (Hint: $SnO_2$ is amphoteric oxide).

Which of the following is not a negatively charged sol?

What happens when gelatin is mixed with a gold sol?

What is the particle size range in a colloidal system?

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

Which ion has the minimum coagulation value?