Question

When negatively charged colloid-like $A{s}_2{S}_3$ sol is added to +vely charged $Fe(OH{)}_3$ sol in suitable amounts:

Correct statement(s) are:

• A. both the sols are precipitated simultaneously
• B. this process is called mutual coagulation
• C. they become positively charged colloid
• D. they become negatively charged colloid

Answer 1

Answer: (A), (B)

The correct options are
A both the sols are precipitated simultaneously
B this process is called mutual coagulation

When -vely charged colloid-like $A{s}_2{S}_3$ sol is added to +vely charged $Fe(OH{)}_3$ sol in suitable amounts both the sols are precipitated simultaneously it is due to the fact that negatively charged particles of the arsenious sulphide sol take up positive ions, resulting in neutralization of the charge on the colloidal particles and hence lowering the stability of the sol and both precipitate simultaneously. This is an example of mutual coagulation.

Hence, option $A$ and $B$ are correct statements.