Correct Answer: B. argillaceous rocks
Solution:
Based on their chemical composition, rocks are classified by their dominant minerals. Rocks in which alumina or clay (argil) are the main constituents are known as argillaceous rocks. Examples include slate and laterite.
Correct Answer: C. cleavage
Solution:
Cleavage is the property of a mineral or rock to break along specific planes of weakness, producing smooth, flat surfaces. This is different from fracture, which is an irregular break. Slate is a classic example of a rock with excellent cleavage.
Correct Answer: C. talc
Solution:
Hardness is measured on the Mohs scale from 1 (softest) to 10 (hardest). Talc is the defining mineral for the softest end of the scale, with a rating of 1. The other options are significantly harder.
Correct Answer: B. argillaceous rock
Solution:
Laterite is a type of rock and soil rich in iron and aluminum, formed in hot and wet tropical areas. Chemically, its primary constituent is clay/alumina, which classifies it as an argillaceous rock.
Correct Answer: B. 10%
Solution:
While a very good quality stone should absorb less than 5% water, the general limit for rejecting a building stone is when its water absorption exceeds 10% of its dry weight. High water absorption indicates higher porosity, which can lead to lower strength and poor durability.
Correct Answer: D. all the above
Solution:
Limestone fits all of these classifications:
- Aqueous rock: It is formed from the deposition of sediments in water.
- Sedimentary rock: This is its primary geological classification based on its formation from sediments.
- Stratified rock: This is a physical classification, as limestone is formed in layers (strata).
Therefore, "all the above" is the correct answer.
Correct Answer: C. monomineralic
Solution:
The term for a rock composed of a single mineral is monomineralic. Conversely, a rock composed of multiple minerals is called polymineralic.
Correct Answer: A. intrusive igneous rock
Solution:
Pegmatite is a type of intrusive igneous rock known for its extremely large crystals. It forms during the final stages of magma crystallization, where the remaining water-rich melt allows crystals to grow to very large sizes.
Correct Answer: B. hardness test of stone
Solution:
Dorry's testing machine is used to determine the hardness or resistance to abrasion of stones. A cylindrical stone sample is subjected to the abrasive action of sand under a specified pressure.
Correct Answer: B. hard
Solution:
Rubble masonry is constructed from rough, undressed stones. Since it is a load-bearing construction, the stones must be hard and durable to ensure the strength and stability of the wall.
Correct Answer: D. 45%
Solution:
Dolomite is a specific type of limestone that is rich in magnesium. By definition, for a limestone to be classified as dolomite, it must contain a significant amount of magnesium carbonate, which can be up to 45%.
Correct Answer: D. 17
Solution:
The coefficient of hardness, determined using Dorry's testing machine, measures a stone's resistance to wear and abrasion. For stones used in road construction, which are subjected to heavy traffic, a high resistance to wear is critical. A coefficient of hardness greater than 17 is required for such applications.
Correct Answer: C. extrusive igneous rock
Solution:
Basalt is a type of igneous rock that forms from the rapid cooling of lava at or near the Earth's surface. Because it forms on the surface, it is classified as an extrusive igneous rock.
Correct Answer: C. igneous rocks
Solution:
Granite is a classic example of an igneous rock. Specifically, it is an intrusive igneous rock, meaning it formed from the slow cooling of magma deep beneath the Earth's surface.
Correct Answer: E. All the above
Solution:
Wedging is a careful quarrying method used for extracting valuable dimension stone without shattering it. It's particularly suitable for stratified rocks (those in layers) that are soft or costly. All the options listed—laterite, marble, limestone, and sandstone—are types of stratified rocks for which this careful extraction method is appropriate to get usable blocks.
Correct Answer: C. white
Solution:
Statuary marble is a high-quality marble prized by sculptors for its purity, fine grain, and translucence. The most famous and sought-after statuary marble, such as Carrara marble from Italy, is pure white.
Correct Answer: C. both (a) and (b)
Solution:
Placing stratified stones with their natural bedding planes parallel to the direction of the load is incorrect practice. The load can easily cause the stone to split along these weak planes. Furthermore, these exposed layers can more easily absorb moisture, leading to faster decay and deterioration.
Correct Answer: C. 100
Solution:
Crushing strength is a critical property for building stones, especially those used in load-bearing structures. A good quality building stone should have a crushing strength of at least 100 MPa (MegaPascals) to ensure it can safely support the loads imposed on it.
Correct Answer: A. Compact sandstone
Solution:
Compact sandstone has the best fire-resisting properties because its quartz grains are cemented by silica, which is highly resistant to heat. Other rocks, like those containing calcium carbonate (marble) or clay (shale), tend to crack or decompose at high temperatures.
Correct Answer: C. hard steel ball
Solution:
The Brinell hardness test involves indenting the test material with a hard steel ball of a standard diameter under a specific load. The diameter of the resulting indentation is then measured to determine the material's hardness. Diamond cones are used in other tests like the Rockwell test.