The void ratio of a soil sample having a porosity of 0.32 and a moisture content of 25% will be................
Try it first: pick an option, then read the explanation.
Correct answer: B. 0.47
Detailed Explanation
Given: porosity n = 0.32. (The stated moisture content of 25% is not needed for this calculation — void ratio depends only on porosity through the geometric relationship e = n/(1−n); it is included as extra information, similar to Q5.)
e = n/(1−n) = 0.32/0.68 = 0.47
Key Concepts for Students
- Once again, e = n/(1−n) is a purely geometric relationship that does not require water content or specific gravity.
- As in Q5, recognizing which given values a formula actually needs (and which are distractors) is itself part of what these questions test.
- A porosity of 0.32 (32%) corresponds to a void ratio of about 0.47 — note how the void ratio value is noticeably larger than the porosity value, consistent with the general pattern discussed in earlier questions.
- If water content were relevant to a follow-up question (e.g., asking for degree of saturation or unit weight), it would need to be combined with this void ratio via eS = wG.