The question asks to classify precious metals within the broader category of minerals. This requires understanding the basic classification of minerals, particularly the distinction between metallic and non-metallic minerals.
Correct Option: B) Metallic minerals. Precious metals like gold, silver, and platinum are characterized by their metallic luster, malleability, ductility, and conductivity, all of which are defining properties of metallic minerals. They are extracted from ores and processed to obtain the pure metal.
The question asks why igneous rocks are called 'primary rocks'. This term relates to their fundamental role in the rock cycle and their origin. We need to evaluate each option based on geological principles.
Correct Option: C) All other rocks (sedimentary and metamorphic) are ultimately derived from them.
This is the correct reason. Igneous rocks are formed directly from the cooling and solidification of magma or lava, which originates from the Earth's interior. They are the first rocks to crystallize from molten material. Subsequently, these igneous rocks can be weathered and eroded to form sediments, which then lithify into sedimentary rocks. Alternatively, igneous rocks (or sedimentary rocks) can be subjected to heat and pressure to form metamorphic rocks. Thus, igneous rocks serve as the original source material for all other rock types in the rock cycle.
The question asks for the meaning of the Latin word 'ignis', from which the English word 'igneous' is derived. To answer this, one needs to recall basic etymology related to geological terms.
Correct Option: D) The word 'igneous' is derived from the Latin word 'ignis', which means 'fire'. This is consistent with the formation of igneous rocks from molten material, which is extremely hot, like fire.
To answer this question, we need to recall the primary characteristics used by geologists to classify igneous rocks. Igneous rocks form from the cooling and solidification of molten rock (magma or lava), and their classification depends on both their chemical composition and their texture.
Correct Option: A) Texture (size of grains/crystals) is a primary characteristic used to classify igneous rocks, as it directly reflects their cooling history.
The question asks about the characteristics of igneous rocks formed when magma cools slowly deep inside the Earth's crust. This involves understanding the relationship between cooling rate, crystal size, and rock type.
C) Coarse-grained intrusive (plutonic) igneous rocks with large crystals. This option accurately describes the characteristics of rocks formed from magma that cools slowly deep within the Earth's crust. The slow cooling allows large crystals to develop, resulting in a coarse-grained texture. These rocks are known as intrusive or plutonic igneous rocks.
The question asks about the type of rock formed when lava cools rapidly on the Earth's surface. This involves understanding the relationship between cooling rate, crystal size, and rock classification.
Correct Option: A) Fine-grained extrusive (volcanic) igneous rocks with small crystals. This option accurately describes the characteristics of rocks formed from rapidly cooled lava on the Earth's surface.