Question

45 Three samples of the same solution are tested, each with a different indicator. All three indicators, bromthymol blue, bromcresol green, and thymol blue, appear blue if the pH of the solution is
(1) 4.7 (2) 6.0 (3) 7.8 (4) 9.9

Answer 1

(4) 9.9 is the most sensible answer.

When an indicator appears blue, that means the solution is basic and the pH of the solution should be within the range of 8 and 14.

Hope this helps~

Answer 2

Answer: The correct answer is Option 4.

Explanation:

Bromothymol blue, Bromocresol green and Thymol blue are the indicators which change their color according to the change in pH of the solution.

The pH range and color change of these indicators are:

1. Bromothymol Blue: The pH range for this indicator is 6.0 to 7.5 and color change is from yellow to blue. It appears yellow below pH 6.0 and blue above pH 7.5
2. Bromocresol green: The pH range for this indicator is 3.5 to 6.0 and color change is from yellow to blue. It appears yellow below pH 3.5 and blue above pH 6.0
3. Thymol Blue: The pH range for this indicator is 8.0 to 9.6 and color change is from yellow to blue. It appears yellow below pH 8.0 and blue above pH 9.6

As, the highest pH of all the indicators is 9.6, so every indicator will appear blue above pH 9.6.

Hence, the correct answer is Option 4.