Question

Which of the given below options is true when milk changes into curd?

Choose the correct option from the following options:

• A. (i) and (ii) are correct
• B. (ii) and (iii) are correct
• C. (i), (iii) and (iv) are correct
• D. (i) to (iv) are correct

Answer 1

The correct option is C

(i), (iii) and (iv) are correct

Step 1: Explanation of the correct option

In the case of option C,

1. The changing of milk into curd is a chemical change since this is an irreversible process.
2. Also, the properties of milk are different from the curd.
3. A chemical change occurs when the molecular composition of the product is completely changed and a new product is formed.
4. When milk turns to curd it changes its shape to semi-solid, and its taste turns sour.
5. After the milk changes into curd, it can not be further converted into milk again so it is a completely irreversible change.

Step 2: Explanation for the incorrect options

In the case of option A,

1. When milk changes into curd its shape changes from liquid to semi-solid.
2. There is no change in the color of curd and milk. Both are white in color.

In the case of option B,

1. The change of milk into curd is an example of chemical change.
2. Also, the shape of milk changes from liquid to semi-solid. As the milk changes into curd its taste becomes sour.

In the case of option D,

1. The shape of curd is semi-solid which is different from the shape of milk which is liquid.
2. Since the change of milk into curd is an example of chemical change so it is an irreversible change. The curd can't be converted into milk again.

Hence, option C is the correct answer.