In an experiment, addition of `4.0mL` of `0.005MBaCl_(2)` to `16.0mL` of arsenious sulphide sol just cause the complete coagulation in `2h` . The flocculating value of the effective ion is:

Options

A. `CI^(-)1.0`
B. `CI^(-), 2.0`
C. `Ba^(2+) 1.0`
D. `Ba^(2+), 0.5`

Answer

C

Explanation

`As_(2)S_(3)` sol is negatively charged owing to preferential adsorption of `S^(2-)`ions. Cation would be the effective ion in coagulation
Flocculating value=minimum milli mol of the effective
on per litre of sol `= 4xx0.005 xx (10^(3))/(4+16)=1.0`