Correct Answer: B. Workability
Solution:
The crushing strength of a stone is an intrinsic property that depends on its physical composition.
- Texture and Specific Gravity: These are direct physical properties. A dense, fine-grained texture and higher specific gravity generally lead to higher crushing strength.
- Workability: This describes the ease with which a stone can be cut, shaped, and dressed. While a desirable quality, it does not determine the stone's ultimate crushing strength. A stone can be easy to work with (high workability) but have low strength, or vice versa.
Correct Answer: C. Kilograms
Solution:
In civil engineering and quarrying operations, the quantity of explosives required for blasting is calculated based on mass. This ensures precise control over the blast's intensity and outcome. Therefore, the amount of explosive material is specified in kilograms (kg).
Correct Answer: C. Marble powder
Solution:
Quarrying involves extracting stone by breaking it apart. This requires explosives or specialized tools.
- Gun powder, Gun cotton (nitrocellulose), and Dynamite are all types of explosives used for blasting rock.
- Marble powder is a by-product obtained from cutting and processing marble. It is a fine dust and has no use in the quarrying process itself; it is a result of it.
Correct Answer: A. Water bound pebbles
Solution:
Shingle refers to a collection of loose, rounded rock fragments, typically pebbles and cobbles, that have been naturally worn and shaped by the action of water. It is commonly found on beaches, riverbeds, and in glacial deposits. Therefore, it is best described as "water bound pebbles."
Correct Answer: B. mechanical, chemical, organic
Solution:
Sedimentary rocks are classified based on their formation process into three main groups:
- Mechanical (or Clastic): Formed from the physical weathering and lithification (compaction and cementation) of rock fragments. Examples include sandstone and shale.
- Chemical: Formed when minerals precipitate from a solution (usually water). Examples include limestone (from calcium carbonate) and rock salt.
- Organic: Formed from the accumulation of organic debris, such as shells, skeletons, or plant matter. Examples include coal and some types of limestone.
The other options refer to different rock classifications: (A) and (C) are classifications of igneous rocks, and (D) describes the layering of rocks (common in sedimentary, but not a sub-classification of them).
Correct Answer: C. Gneiss
Solution:
The process of transformation under heat and pressure is called metamorphism. Granite, an igneous rock, is composed of minerals like feldspar, quartz, and mica. When subjected to intense heat and pressure, these minerals recrystallize and align into bands, transforming the granite into Gneiss, a foliated metamorphic rock.
- Marble is formed from the metamorphism of limestone.
- Slate is formed from the metamorphism of shale.
- Quartzite is formed from the metamorphism of sandstone.
Correct Answer: C. Blasting Powder
Solution:
The composition described (Saltpetre/Potassium Nitrate, Sulphur, and Charcoal) is the classic formula for Blasting Powder, also known as black powder. This was one of the earliest known chemical explosives and is used for quarrying and blasting operations.
- Dynamite: Its primary explosive component is nitroglycerin.
- Nitrocellulose: Also known as guncotton, it's a different type of explosive.
- Cordite: A smokeless propellant made from nitroglycerin and guncotton.
Correct Answer: A. Slate
Solution:
Slate is the most suitable stone for damp-proofing. It is a metamorphic rock that is extremely dense, non-porous, and has a layered (foliated) structure. These properties make it highly resistant to water penetration, which is why it has been traditionally used for roofing, flooring, and as a damp-proof course (DPC) in walls.
- Laterite, Marble, and Granite are more porous than slate and can absorb moisture, making them less suitable for damp-proofing applications.
Correct Answer: C. Abrasion resistance
Solution:
The Los Angeles (L.A.) abrasion test is a widely used method to determine the toughness and abrasion resistance of aggregates. The test involves placing a sample of aggregate in a rotating steel drum with steel spheres. As the drum rotates, the spheres and the aggregates tumble, causing the aggregate particles to wear down. The percentage of material worn away is calculated, which indicates the aggregate's resistance to abrasion.
- Crushing strength is determined by the aggregate crushing value test.
- Impact value is determined by the aggregate impact test.
- Water absorption measures the porosity of the aggregate.