Which of the following is most effective for the coagulation of $Pt$ sol?

The polar head part of sodium stearate is ...... .

Identify the option having the correct set of True $(T)$ or False $(F)$ statements with respect to colloidal solutions:
$(I)$ Lyophobic colloids are heavily solvated by the dispersion medium.
$(II)$ Multimolecular colloids are usually lyophilic.
$(III)$ Surface tension of a starch aqua sol will be lesser than that of water.
$(IV)$ Blood gets coagulated by the addition of $NaCl$.

Assertion : The micelle formed by sodium stearate in water has $-COO^{-}$ groups at the surface.
Reason : Surface tension of water is reduced by the addition of stearate.

If the dispersed phase is a liquid and the dispersion medium is a solid,the colloid is known as

Which of the following metal nanoparticles is used for coating the filter material that acts as an effective bacterial disinfectant?