Why are there so many substances?

first conclusion was that the whole world is made up of only 4 elements but as the time passed more elements were discovered... if the world would not contain more elements... you wouldn't be alive.

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l