The capillary rise in soil (h, cm) with average pore radius (r, cm) is related as:

Correct option is A

Explanation of the Correct Option (a): hr = 0.15
· Capillary rise of water in soil pores follows Jurin’s Law, which states:
· Capillary rise is inversely proportional to pore radius.
· The general capillary rise equation is:

where
· h = capillary rise
· T = surface tension of water
· θ = contact angle (≈ 0° for soil water)
· ρ = density of water
· g = acceleration due to gravity
· r = pore radius
For soil water under normal conditions, this equation simplifies to:

· Hence, the correct relationship is hr = 0.15.
Explanation of Other Options
Option (b): hr = 1.5
· Incorrect because:
· Overestimates capillary constant by ten times.
Option (c): hr = 0.30
· Incorrect:
· Not supported by standard soil physics derivation.
Option (d): hr = 3.0
· Incorrect:
· Far beyond realistic capillary rise values in soils.
Key Points Related to the Question
· Capillary rise is higher in fine-textured soils (small pore radius).
· Sandy soils → low capillary rise
· Clay soils → high capillary rise
· Relationship: h ∝ 1/r