Question

Identify the change in colour, when curd is tested with litmus paper.

• A. Red litmus to green.
• B. Blue litmus to red.
• C. Red litmus to blue.
• D. Blue litmus to green.

Answer 1

The correct option is B

Blue litmus to red.

Curd contains lactic acid. $$\begin{array}{ccc}\text{Litmus paper}& \text{Colour in acidic solution}& \text{Colour in basic solution}\\ \text{Red}& \text{Red (no change)}& \text{Red to blue}\\ \text{Blue}& \text{Blue to red}& \text{Blue (no change)}\end{array}$$Therefore, blue litmus paper turns red when dipped in curd.