NDA 2025
- Exam
- NDA
- Year
- 2025
- Subject
- General Ability
- Chapter
- General Studies
NDA 2025 · General Ability · General Studies
Consider the following pairs with reference to sedimentary rocks...
Consider the following pairs with reference to sedimentary rocks and the process of their formation:
1. Chert — Chemically formed
2. Geyserite — Organically formed
3. Shale — Mechanically formed
Which of the pairs given above is/are correctly matched?
1. Chert — Chemically formed
2. Geyserite — Organically formed
3. Shale — Mechanically formed
Which of the pairs given above is/are correctly matched?
Options
- A1 only
- B1 and 2 only
- C2 and 3 only
- D1, 2 and 3
Correct answer
D. 1, 2 and 3
Step-by-step solution
Sedimentary rocks are classified into three major groups based on their mode of formation:
1. Chemically formed: These rocks are formed by the precipitation of minerals from water. Examples include chert, limestone, halite, and potash. Thus, pair 1 is correctly matched.
2. Organically formed: These rocks are formed from the accumulation of plant and animal debris. Examples include geyserite, chalk, limestone, and coal. Thus, pair 2 is correctly matched.
3. Mechanically formed: These rocks are formed from the mechanical weathering of pre-existing rocks, followed by transportation and deposition. Examples include sandstone, conglomerate, limestone, shale, and loess. Thus, pair 3 is correctly matched.
All three pairs are correctly matched.
Answer: 1, 2 and 3
1. Chemically formed: These rocks are formed by the precipitation of minerals from water. Examples include chert, limestone, halite, and potash. Thus, pair 1 is correctly matched.
2. Organically formed: These rocks are formed from the accumulation of plant and animal debris. Examples include geyserite, chalk, limestone, and coal. Thus, pair 2 is correctly matched.
3. Mechanically formed: These rocks are formed from the mechanical weathering of pre-existing rocks, followed by transportation and deposition. Examples include sandstone, conglomerate, limestone, shale, and loess. Thus, pair 3 is correctly matched.
All three pairs are correctly matched.
Answer: 1, 2 and 3