Question:
$100 \mathrm{ml}$ of $0.0018 \%(\mathrm{w} / \mathrm{v})$ solution of $\mathrm{Cl}^{-}$ion was the minimum concentration of $\mathrm{Cl}^{-}$required to precipitate a negative sol in one $\mathrm{h}$. The coagulating value of $\mathrm{Cl}^{-}$ion is _________(Nearest integer)
Solution:
Official Ans. by NTA (1)