_______ is the colour of litmus solution when it is neither acidic nor basic.

The correct answer is Purple.

Key Points

• Litmus solution is used as an indicator to test whether a solution is acidic or basic.
• Litmus solution turns red under acidic conditions and blue under basic conditions.
• When the solution is neither acidic nor basic, it remains purple.

Additional Information

• Litmus paper is another form of litmus test, which also changes color depending on the pH of the solution.
• Other indicators like phenolphthalein and methyl orange are also used to determine the pH of a solution.
  • Phenolphthalein turns pink in basic solutions and is colorless in acidic solutions.
  • Methyl orange turns red in acidic solutions and yellow in basic solutions.