Question

A small quantity of curd is added to warm milk. The milk is stirred and is set aside for few hours at a warm place. In a few hours, the curd is formed. This is an irreversible change because

• A. Curd cannot be converted back to milk.
• B. Curd can be converted back to milk.
• C. Sometimes curd can be reverted back to milk and sometimes not.
• D. No change is happening.

Answer 1

The correct option is A

Curd cannot be converted back to milk.

Irreversible changes are permanent changes that cannot be undone. An irreversible change starts with one material and ends up with one or more new ones. The same way a milk when converted to curd it changes from one material to another ( i.e. from milk to curd ) and these changes cannot be undone. Hence, an irreversible reaction.