# In a coagulation experiment $5 \;mL$ of $\;As_{2}S_{3}\;$ is mixed with disfilled water and $0.1\; M$ solution of an electorlyte $AB$ so that total volume is $10\; mL$ . It was found that all solutions containing more than $4.6\; mL$ of $AB$ coagulate with in $5$ minutes . What is the flocculation value of $AB$ for $\;As_{2}S_{3}\;$ sol ?

$(a)\;44\qquad(b)\;46\qquad(c)\;43\qquad(d)\;4$

Answer : $46$
Explanation :
A minimum of 4.6 mL of AB is required to coagulate the sol . The moles of AB in the sol is
$=\large\frac{4.6 \times 0.1}{10}=0.046\;moles$
This means that a minimum of 0.046 moles or $\;0.046 \times 1000 = 46\;$milli moles are required for coagulating 1 litre of sol .
Therefore , Flocculation value of AB for $\;As_{2}S_{3}\;$ sol = 46 .