Difficulty: Easy
Correct Answer: Both A and R are true and R is the correct explanation of A.
Explanation:
Introduction / Context:
This question relates to everyday science and safety in the home. It concerns liquefied petroleum gas (LPG) used for cooking and how people are able to notice a gas leak before it becomes too dangerous. The assertion–reason format tests both factual understanding and whether students know why the gas can be detected by smell.
Given Data / Assumptions:
Concept / Approach:
Pure LPG is actually odourless. For safety, a substance with a strong smell, often a sulfur containing compound, is added to LPG so that even a small leak can be noticed quickly by people. Thus, the ability to detect leaks is directly connected with the strong smell intentionally given to the gas supply.
Step-by-Step Solution:
Step 1: Evaluate Assertion (A). People commonly notice gas leaks in kitchens or near cylinders because of a characteristic smell and then take action to close the valve or ventilate the area. This shows that leakages in household gas cylinders can indeed be detected by the sense of smell. So A is true.Step 2: Evaluate Reason (R). The statement says that LPG has a strong smell. In practice, the LPG supplied for domestic use has a distinct, strong odour because of added odorant. At user level, it is fair to say that LPG has a strong smell. So R is also true in this context.Step 3: Check whether R explains A. The very reason people can detect leaks is that the gas they use has this strong smell. If the gas were completely odourless, small leaks would be much harder to notice without special instruments. Therefore, the presence of a strong smell is exactly the factor that allows leak detection.Step 4: Hence both A and R are true and R is the correct explanation of A at this level of discussion.
Verification / Alternative check:
If LPG supplied to homes had no smell at all, one could not reliably detect leaks by nose. The fact that safety warnings and advice tell people to “smell for gas” confirms that the intentionally added smell is the method of detection. This matches the structure of the assertion and reason and supports the explanatory relationship.
Why Other Options Are Wrong:
Option b says that R is not the explanation, which ignores the direct link between the smell and detection. Options c and d require one of the statements to be false, which conflicts with both scientific practice in gas supply and everyday experience of gas leaks.
Common Pitfalls:
Some students may know that pure LPG is odourless and then wrongly conclude that the reason is false. However, exam questions of this type usually refer to LPG as supplied and used in homes, which does have a smell due to added odorant. It is important to interpret such statements in the practical sense intended by the syllabus.
Final Answer:
The correct evaluation is that both Assertion (A) and Reason (R) are true and R is the correct explanation of A.
Discussion & Comments