Which of the following is a water-in-oil $(W/O)$ type of emulsion?

The coagulation of $10 \, mL$ of gold sol is prevented by the addition of $0.025 \, g$ of starch to it before adding $1 \, mL$ of $10 \% \, NaCl$ solution. The gold number of starch is .............

The gold numbers of $A, B, C$ and $D$ are $0.04, 0.002, 10$ and $25$ respectively. The protective power of $A, B, C$ and $D$ are in the order:

Colour is imparted to glass by mixing

The gold numbers of $A, B, C$ and $D$ are $0.04, 0.002, 10$ and $25$ respectively. What is the order of their protective power?

The Tyndall effect depends upon the