What is Ph?
Ph stands for potential of hydrogen and is a measure of concentration of hydrogen ions. It is a scale used to specify if a solution is acidic, basic or alkali.

Range of Ph?
The Ph scale ranges from 0-14. Solutions having a Ph between 0-7 is on the Ph scale is termed as acidic. Solutions which are closer to 0 are said to be strongly acidic and as the Ph increases from 0 to 7 the acidity of the solution decreases.
Solutions having a Ph of 7 is termed as neutral.
Solutions having a Ph between 7-14 is termed as alkali or base. The basicity of a solution increases as the value of the Ph increases from 7 to 14.

What is used as an indicator of Ph?
Litmus paper is used as an indicator of Ph of the solution. A litmus paper changes in color according to the Ph of the solution. A blue litmus paper when dipped in solution turns into red when the solution is acidic. A red litmus paper turns into blue when the solution is basic. Purple color of litmus paper indicates neutral solution.
 
Examples of Acidic Ph
Oxalic Acid
Mono Ammonium Phosphate
 
 
Examples of Basic Ph
Di Ammonium Phosphate
Sodium Oxalate

 
Examples of neutral Ph
Water