Question

Choose the correct statement regarding Phenolphthalein indicator:

• A. Colour transition range is nearly $(8.3-10)$
• B. Colour transition range is nearly $(3.2-4.4)$
• C. Colour transition range is nearly $(5-6.7)$
• D. Colour transition range is nearly $(12.2-14)$

Answer 1

The correct option is A Colour transition range is nearly $(8.3-10)$

Colour transition range (CTR):
It is the pH range between which the indicator changes its colour.

$\text{Indicator}\text{CTR}\text{Methyl Orange}3.2-4.4\text{Phenolphthalein}8.3-10\text{Phenol Red}6.4-8.2\text{Bromothymol}6.2-7.4$