Q110. What description applies to soils with pH greater than 7.5?
[SSC MTS (30 October 2024, Shift 3)]
- (A) Slightly acidic
- (B) Alkaline
- (C) Strongly acidic
- (D) Neutral
Answer: (B) Alkaline
Explanation: A pH above seven indicates alkalinity; soils exceeding 7.5 are distinctly alkaline. In arid and semi-arid regions, evaporation and accumulation of soluble salts or carbonates can raise soil pH, sometimes making important micronutrients less available to crops.
Q109. Which process chiefly initiates the development of soil from rock?
[SSC MTS (18 October 2024, Shift 1)]
- (A) Weathering
- (B) Irrigation
- (C) Degradation
- (D) Mining
Answer: (A) Weathering
Explanation: Physical, chemical and biological weathering break down parent rock into mineral fragments and altered materials. Organic inputs and soil-forming organisms then help create horizons over time. Irrigation and mining may modify existing soil but are not the primary natural origin.
Q108. Which listed element becomes highly concentrated in laterite profiles?
[SSC MTS (17 October 2024, Shift 2)]
- (A) Iron
- (B) Feldspar
- (C) Nitrogen
- (D) Lime
Answer: (A) Iron
Explanation: Intense tropical leaching removes many soluble compounds while iron and aluminium oxides remain relatively concentrated. Iron compounds impart reddish coloration to many laterite soils. Nitrogen and lime are generally depleted rather than enriched by the process.
Q107. Which property expresses the ability of soil or rock to transmit a fluid?
[SSC MTS (16 October 2024, Shift 2)]
- (A) Permeability
- (B) Plasticity
- (C) Stability
- (D) Density
Answer: (A) Permeability
Explanation: Permeability describes fluid movement through connected pore spaces and depends on grain size, pore connectivity and compaction. It differs from porosity, which measures how much empty space exists. Coarse sands often permit faster drainage than dense clays.
Q106. What is the layer of loose rock debris and soil covering solid bedrock called?
[SSC MTS (9 October 2024, Shift 2)]
- (A) Talus
- (B) Regolith
- (C) Scree
- (D) Protolith
Answer: (B) Regolith
Explanation: Regolith is the blanket of unconsolidated weathered material lying above intact bedrock. It may contain fragmented rock, dust and developing soil. Talus and scree refer more specifically to accumulations of rock fragments near slopes or cliffs.
Q105. Which claim about deposits of alluvial soil is generally incorrect?
[MP Vyapam Sub Engineer Civil (23 September 2024, Shift 2)]
- (A) They form through stream-borne sediment
- (B) They commonly form extensive even ground
- (C) They often have gentle surface slopes
- (D) Hard, shallow bedrock foundations are always available
Answer: (D) Hard, shallow bedrock foundations are always available
Explanation: Alluvial terrain is built by deposition of unconsolidated river sediment, often producing flat landforms. Such deposits can be deep or compressible, so hard foundation strata are not necessarily near the surface. Engineering properties vary with sediment texture and depth.
Q104. Of calcium, phosphate, potash and nitrogen, which was identified in the NDA paper as appreciable in Indian laterite?
[UPSC NDA II, General Ability Test (1 September 2024)]
- (A) Calcium
- (B) Phosphate
- (C) Potash
- (D) Nitrogen
Answer: (C) Potash
Explanation: This multiple-choice examination selected potash relative to the other listed nutrients. The defining property of laterite remains intense leaching with enrichment of iron and aluminium oxides. Lateritic fertility varies, and many soils still require nutrient amendments for cultivation.
Q103. Halophytes typically grow in which category of soil?
[UPSC CDS-II General Knowledge (1 September 2024)]
- (A) Acidic soil
- (B) Saline soil
- (C) Black soil
- (D) Sandy soil
Answer: (B) Saline soil
Explanation: Halophytes are plants adapted to environments with high soluble-salt concentration. They occur around salt marshes, saline flats and certain coasts. Adaptations may include selective ion uptake, salt exclusion and storage in specialised tissues, unlike ordinary salt-sensitive crop plants.
Q102. Consider two statements: 1. Bajra is mainly grown in Rajasthan, Uttar Pradesh and Gujarat, whereas ragi is important in Karnataka and Tamil Nadu. 2. Bajra suits sandy and shallow black soils, while ragi suits red and shallow black soils. Which is correct?
[UPSC CDS-II General Knowledge (1 September 2024)]
- (A) Both are correct, and 2 correctly explains 1
- (B) Both are correct, but 2 does not correctly explain 1
- (C) Statement 1 only is correct
- (D) Statement 2 only is correct
Answer: (B) Both are correct, but 2 does not correctly explain 1
Explanation: Bajra tolerates drought and grows on sandy or relatively shallow soils, while ragi grows on several well-drained soils including red soil. The regional cultivation patterns are valid, but soil suitability alone does not fully explain where each millet is grown.
Q101. Which state is not part of the usual black-soil distribution?
[WBCS 2023 Mains, Paper III (18 August 2024)]
- (A) Maharashtra
- (B) Andhra Pradesh
- (C) Gujarat
- (D) West Bengal
Answer: (D) West Bengal
Explanation: Black regur soils are predominantly distributed across the Deccan and adjoining western and central Indian regions. West Bengal instead has extensive alluvial plains and lateritic tracts. This comparison highlights the geographical link between black soil and basaltic landscapes.
