Question

In which of the following entropy decreases?
(A) Preparing aqueous solution of common salt
(B) Change of water into ice
(C) Dry ice placed in an open vessel
(D) Melting of ice

Answer 1

Entropy can understood as the measure of randomness or disorder in a system. The more randomness in a system means the entropy of the system is higher.

let's understand the options in an easy way:

(A) Preparing aqueous solution of common salt
- here, solid NaCl is mixed with water to form an aqueous solution. So randomness is increasing. hence entropy is increasing.

(B) Change of water into ice- matter in solid state are more organized. Hence randomness is decreasing here: Entropy decreases.

(C) Dry ice placed in an open vessel: Solid carbon dioxide will turn into gaseous carbon dioxide. Randomness will increase: Entropy increases.

(D) Melting of ice: Solid to liquid transformation. So randomness increases: entropy increases.


So Your answer is (B) Change of water into ice.

Answer 2

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Entropy can understood as the measure of randomness or disorder in a system. The more randomness in a system means the entropy of the system is higher.

let's understand the options in an easy way:

(A) Preparing aqueous solution of common salt

- here, solid NaCl is mixed with water to form an aqueous solution. So randomness is increasing. hence entropy is increasing.

(B) Change of water into ice- matter in solid state are more organized. Hence randomness is decreasing here: Entropy decreases.

(C) Dry ice placed in an open vessel: Solid carbon dioxide will turn into gaseous carbon dioxide. Randomness will increase: Entropy increases.

(D) Melting of ice: Solid to liquid transformation. So randomness increases: entropy increases.

So Your answer is

(B) Change of water into ice.