Which of the following is/are the example/examples of chemical change?

  1. Crystallization of sodium chloride
  2. Melting of ice
  3. Souring of milk

Select the correct answer using the code given below.

[UPSC Civil Services Exam – 2014 Prelims]

(a) 1 and 2 only

(b) 3 only

(c) 1, 2 and 3

(d) None


Answer: (b)        

Explanation:

  • Crystallization of sodium chloride – It is a physical change since sodium chloride does not transform into some other chemical element after crystallization.
  • Melting of ice – It is not a chemical change since the composition of water molecules stays the same before and after melting.
  • Souring of milk – Lactic acid bacteria ferment lactose at room temperature and turn it into lactic acid. As a re­sult, the acid­i­ty of the milk in­creas­es, which in its turn caus­es the pro­tein to fold and liq­uid to sep­a­rate into whey and a vis­cous mass. The soured milk has new elements and it cannot be reversed. Hence, it is a chemical change.

Consider the following statements:                                                                   The Parliament of India can place a particular law in the Ninth Schedule of the Constitution of India. The validity of a law placed in the Ninth Schedule cannot be examined by any court and no judgement can be made on it. Which of the statements given above is/are correct?

Consider the following statements:                                               

Read More »

Consider the following statements:                                                         The Parliament of India can place a particular law in the Ninth Schedule of the Constitution of India. The validity of a law placed in the Ninth Schedule cannot be examined by any court and no judgement can be made on it. Which of the statements given above is/are correct?

Consider the following statements:                                               

Read More »
Loading...
Left Menu Icon