1. Assertion (A): Large cold storage plants use ammonia as refrigerant while domestic refrigerators use chlorofluorocarbons.
2. Reason (R): Ammonia can be liquified at ambient temperatures at low pressures.
A
Both A and R are true, and R is the correct explanation of A
B
Both A and R are true, but R is not a correct explanation of A
C
A is true, but R is false
D
A is false, but R is true
Correct Answer: Option C
Explanation
1. Assertion (A): It states that large cold storage plants typically use ammonia as a refrigerant, whereas domestic refrigerators commonly used chlorofluorocarbons (CFCs) (around the time this question was posed, though CFCs were being phased out). This statement reflects the common practice at the time; ammonia is efficient but toxic, hence used industrially, while CFCs/HCFCs/HFCs were used domestically. So, Assertion (A) is true.
2. Reason (R): It states that Ammonia can be liquified at ambient temperatures but at low pressures. This is false. Ammonia can be liquefied at ambient temperatures (its critical temperature is high, 132.4 °C), but it requires relatively *high* pressures (e.g., ~8.5 atm at 20°C) to liquefy, not low pressures.
3. Since Assertion (A) is true and Reason (R) is false, the correct option is (C).