Question

Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R).
Assertion (A): In a double ring infiltrometer, the double ring avoids requirement of deep insertion into the soil.
Reason (R): The outer ring provides a buffer of infiltrating water, which leads to the force of infiltration below the inner ring remaining completely vertical and unidirectional.
In light of the above statements, choose the correct answer from the options given below.

• 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 the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Insertion depth requirements do not change with a double ring, the outer ring's real job is stopping sideways spreading of water under the inner ring.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
This question is about why a double ring infiltrometer uses two rings instead of one, and whether that design choice has anything to do with how deep the rings must be pushed into the soil.

Step 2: Key Formula or Approach:
An infiltrometer ring, single or double, is always driven a certain depth into the soil (commonly a few centimetres to about 15 cm) so that water cannot leak sideways along the gap between the ring wall and the soil. This insertion depth requirement exists for any ring and does not disappear just because a second ring is added.
The real purpose of the outer ring in a double ring infiltrometer is to keep the soil around the inner ring saturated with water at the same time as the inner ring, so that water infiltrating from the inner ring cannot spread out sideways underground.

Step 3: Detailed Explanation:
Assertion (A) claims the double ring design removes the need to insert the rings deeply. This is false, both the inner and outer rings still need to be driven in enough to stop water escaping sideways under the ring wall itself, the double ring setup does not change this requirement at all.
Reason (R) describes the actual reason double rings are used: the outer ring keeps a buffer of ponded, infiltrating water around the inner ring, this buffer stops the water below the inner ring from bulging outward, and forces it to keep moving straight down in a purely vertical, one directional path. This is exactly the accepted explanation for the double ring design, so (R) is true.
Because (A) is false while (R) is a true and correct fact about how double ring infiltrometers work, only option 4 fits, both option 1 and option 2 require (A) to be true, and option 3 wrongly calls (R) false.

Step 4: Final Answer:
(A) is false, since insertion depth is still required regardless of ring number, while (R) is true, since the outer ring genuinely forces vertical, unidirectional flow below the inner ring, so the answer is option 4.