When the litmus solution is neither acidic nor basic then its colour is ______.

purple

The correct answer is option 1. purple.

When the litmus solution is neither acidic nor basic, its color is purple. This color indicates that the solution is neutral, meaning it has a pH value around 7. Litmus is a pH indicator that turns red in acidic solutions and blue in basic solutions. In a neutral solution, litmus retains its original purple color.