State the characteristics of hard soap and soft soap

How to know valencies of elements of variable valencies in a compound? Ex- lead oxide. Here what should we take the valency of lead?

In a metal chloride, the weight of metal and chlorine is in the ratio of 1:2. The equivalent weight of the metal will be:

(A) 71

(B) 35.5

(C) 106.5

(D) 17.75

Concentration of 1 mg per litre is equal to _________ ppm.

Draw molecular orbital diagram for ${{F}_{2}}$ molecule. Also, gives its electronic configuration, bond order and magnetic property.