Muddy water can be purified through coagulation using

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$ : The diameter of colloidal particles in solution should not be much smaller than the wavelength of light to show Tyndall effect.
Reason $R$ : The light scatters in all directions when the size of particles is large enough.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following is a colloid?

Gold sol is not a

When an excess of $AgNO_3$ solution is added to a $KI$ solution,a sol is formed. The colloidal particles will carry which type of charge?

The coagulating power of electrolytes having ions $Na^{+}$, $Al^{3+}$, and $Ba^{2+}$ for $As_{2}S_{3}$ sol increases in the order