Question

Universal indicator shows yellow colour when added to a solution at ${25}^{0}C$. If its concentration is changed such that the same indicator shows red colour, then identify the correct statement.

• A. The solution is diluted to 100 times
• B. The solution is concentrated by 100 times
• C. The solution is concentrated 10,000 times
• D. The solution is concentrated 1,00,000 times

Answer 1

Answer: (C)

The solution is concentrated 10,000 times

To change colour of universal indicator from yellow to red, $pH$ need to be increased by 4 times, i.e., $\left[H^{+}\right]$ increases by ${10}^4$ times.