Q70. Which statement about soil-forming factors is incorrect?
[RRB Group D (29 September 2022, Shift 2)]
- (A) Temperature and rainfall affect weathering
- (B) Time influences soil-profile development
- (C) Parent rock can influence soil colour
- (D) Altitude and slope directly determine humus formation rate
Answer: (D) Altitude and slope directly determine humus formation rate
Explanation: Humus formation mainly depends on organic residues, microorganisms, moisture and temperature. Altitude and slope influence these indirectly through climate, vegetation and runoff, but they are not the sole direct determinants. Parent material influences many inherited mineral properties.
Q69. Which soil covers about forty percent of India’s geographical area?
[RRB Group D (27 September 2022, Shift 3)]
- (A) Alluvial
- (B) Black
- (C) Red and yellow
- (D) Laterite
Answer: (A) Alluvial
Explanation: Alluvial soils are the most widespread of the familiar Indian soil groups. They occupy large river valleys, the northern plains and several coastal deltas. They consist of transported sediments and support intensive agriculture owing to generally favorable properties.
Q68. Which option is an abiotic part of an ecosystem?
[RRB Group D (14 September 2022, Shift 2)]
- (A) Fungi
- (B) Soil
- (C) Microorganisms
- (D) Insects
Answer: (B) Soil
Explanation: Soil is classified as an abiotic environmental component even though it contains living organisms. Its nonliving matrix of minerals, water, gases and organic material provides a medium for plant growth. Fungi, insects and microorganisms themselves are biotic constituents.
Q67. Which is not a biotic ecosystem component?
[RRB Group D (18 August 2022, Shift 1)]
- (A) Frog
- (B) Flower
- (C) Insect
- (D) Soil
Answer: (D) Soil
Explanation: An ecosystem contains biotic organisms and abiotic conditions. Frogs, flowers and insects are living components, whereas soil as an environmental medium is grouped with air, water and minerals. Soil may house many organisms, but that does not change its category in this question.
Q66. Which soil mainly forms the Northern Plains of India?
[SSC MTS (25 July 2022, Shift 2)]
- (A) Laterite
- (B) Arid
- (C) Alluvial
- (D) Black
Answer: (C) Alluvial
Explanation: Alluvial soil is formed through the accumulation of river-transported sediment. Large Himalayan river systems deposited sand, silt and clay over the northern lowlands. Older alluvium is known as bhangar, and relatively young floodplain deposits are called khadar.
Q65. Which factor most strongly determines the initial mineral content, texture and colour of soil?
[SSC MTS (22 July 2022, Shift 1)]
- (A) Parent rock
- (B) Time
- (C) Relief
- (D) Climate
Answer: (A) Parent rock
Explanation: The parent rock or sediment supplies the original minerals from which a soil develops. Its composition and grain characteristics influence colour, chemistry and texture. Climate, time, organisms and relief subsequently transform the material into a differentiated soil profile.
Q64. Which listed item is not one of the five standard soil-forming factors?
[DSSSB PRT (20 March 2022, Shift 1)]
- (A) Soil composition
- (B) Parent material
- (C) Time
- (D) Climate
Answer: (A) Soil composition
Explanation: Standard soil-forming factors include climate, organisms, relief or topography, parent material and time. Soil composition is largely an outcome of those factors rather than a separate independent factor. Their relative influence determines soil properties across differing landscapes.
Q63. Which statement is incorrect if it claims to describe the composition of soil completely?
[SSC GD Constable (9 December 2021, Shift 1)]
- (A) Soil contains only inorganic matter
- (B) Soil covers much of Earth’s land surface
- (C) Soil is commonly a granular surface layer
- (D) Soil contains minerals
Answer: (A) Soil contains only inorganic matter
Explanation: Natural soil contains both mineral particles and organic constituents, alongside air, water and living organisms. Therefore, describing it as purely inorganic is incomplete. The balance of its components determines texture, nutrient cycling, water storage and biological productivity.
Q62. Among clay, sand, silt and loam, which soil material typically retains the greatest amount of water?
[SSC GD Constable (6 December 2021, Shift 1)]
- (A) Clay
- (B) Sand
- (C) Silt
- (D) Loam
Answer: (A) Clay
Explanation: Clay consists of extremely fine particles with large combined surface area and small pore spaces. It commonly holds more total water than sand or silt. Not all stored water is equally available to plants, a distinction important for irrigation decisions.
Q61. Which soil in southern Indian states is especially associated with cashew cultivation?
[SSC GD Constable (3 December 2021, Shift 3)]
- (A) Arid soil
- (B) Black soil
- (C) Alluvial soil
- (D) Red laterite soil
Answer: (D) Red laterite soil
Explanation: Red lateritic soils occur in humid, strongly weathered parts of peninsular India. Suitable sites in Kerala, Tamil Nadu and Andhra Pradesh can support cashew. Although laterites are often nutrient-poor, appropriate site conditions and management enable plantation crops.
