What is the difference between a simple cell and a galvanic cell?

Those solutions which are standardized by the titration with the primary standard solution are called a secondary standard solution.

The examples of the secondary standard solution are:

1. Decinormal H2SO4 solution
2. Normal NaOH solution

When, Ionic Product > Solubility product, precipitation occurs.

Riemann's green is a green pigment ZnO.CoO, which is obtained by heating a mixture of zinc oxide and cobalt nitrate or by the reaction of cobalt nitrate with either 3Zn(OH)2ZnCO3 or zinc sulphate.

Sigma bond is stronger than Pi bond because of the following reasons:

1. The extent of overlapping in Sigma bond is greater than in Pi bond.
2. The electron density in intermolecular axis is more in Sigma bond than in Pi bond.
3. There is free rotation of atom about Sigma bond but not about Pi bond.

Systems refers to the specific part of the universe comprising of interdependent or interlinked components which are of special interest to us. 

For example: Various parts performing various tasks have been put together to create a well-functioning car, so, "car" is a system.

Surrounding refers to the area around any object, place or being taken as a reference. 

Option 2 is correct ans .

Dissociation of water is an endothermic  reversible reaction.

When temperature is increased , for an endothermic reaction in equilibrium , it shifts the equilibrium to forward direction i.e. more product is formed which in this case means : more water is dissociated ( more H+  concentration ) is obtained . Ph= negative logarithm of H+ concentration so, more H+ concentration means, lesser Ph. so , whole ph range gets changed when temperature is increased...