JEE Main levelSingle correct optionDifficulty 2 of 3bm095
Assertion (A): Curdling of milk is an example of denaturation of protein. Reason (R): Lactic acid produced by bacteria lowers the pH and unfolds the milk protein, so it precipitates.
ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true
Answer: A
The lactic acid formed from lactose by bacteria changes the pH, which disrupts the weak interactions of milk proteins (casein), and the unfolded protein coagulates. So A is true and R explains it.