Answer: (4) 10
Changing the colour of red litmus paper to blue is a general property of the alkaline solution. pH scale gives information about the acidic basic and neutral solution.
- Solutions having a value of pH ranging 0 to 7 on pH scale are termed as an acidic solution.
- Solutions having a value of pH ranging 7 to 14 on pH scale are known as basic solutions.
- Solutions having the value of pH equal to 7 on pH scale are known as neutral solutions.