Question

Given below are five statements about soil pH:

(A) Majority of red soils are loams with pH values ranging between 5.0 to 8.0.

(B) Laterite soils, which are generally acidic, have an average pH range between 6.0 to 7.0.

(C) Red and yellow soils have a pH around neutrality or else slightly on the acidic side.

(D) Desert soils have a fairly high pH and varying amounts of calcium carbonate.

(E) Alkali soils have a high pH which may range between 7.0 and 8.0.

Choose the correct answer from the options given below:

• A. (A), (C) and (D) only.
• B. (A), (B) and (C) only.
• C. (C), (D) and (E) only.
• D. (B), (C) and (D) only.

Hint:

Recall the typical pH band associated with red, laterite, desert and alkali soils.

Answer 1

The Correct Option is A

Go soil type by soil type and recall the pH band each one is known for.

Red soils, mostly loamy, are described in soil surveys as ranging from mildly acidic to mildly alkaline, roughly pH 5.0 to 8.0, so (A) matches this well.

Laterite soils form under heavy rainfall and intense leaching, which strips away bases and leaves the soil strongly acidic, typically well under pH 6.0. Placing their average at 6.0 to 7.0 undersells how acidic they actually are, so (B) does not hold.

Red and yellow soils are usually reported as close to neutral or slightly acidic, which is exactly what (C) states, so it checks out.

Desert soils develop under low rainfall with little leaching, so bases and calcium carbonate accumulate, giving them a fairly high, alkaline pH, matching (D).

Alkali or sodic soils carry excess exchangeable sodium, which pushes their pH much higher than ordinary alkaline soils, commonly above 8.5, so the modest 7.0 to 8.0 range claimed in (E) is too low to be correct.

So the statements that hold up are (A), (C) and (D).

\[\boxed{(A),\ (C),\ (D)\ \text{only}}\]