Rocks and Earth Materials

Petroleum forms from the remains of marine organisms that settle on ocean floors and get buried under sedimentary layers over millions of years. This process occurs only in sedimentary basins, making sedimentary rocks the primary source rocks for oil and gas. Metamorphic, plutonic, and volcanic rocks do not have the right conditions for petroleum formation.

Prismatic sulfur (also known as monoclinic sulfur) forms needle-shaped crystals when it crystallizes. This is one of the crystalline allotropes of sulfur.

A pediment is a gently inclined rocky surface found at the foot of mountains, often covered with a thin layer of debris. This is a distinct geomorphological feature in arid and semi-arid regions. Pediplains are more extensive erosional surfaces, while barchans and seifs are types of sand dunes.

Rocks are made up of various minerals. Out of about 2000 different minerals, only 12 minerals are common all over the world. These 12 rock forming minerals are called 'rock formers'.

Igneous rocks are also called ‘primary rocks’ because they were the first ones to be formed. ‘Extrusive igneous rock’ is the name given to magma erupting and solidifying on reaching the earth’s surface. As magma cools down rapidly on reaching the earth’s surface, so these rocks are very fine-grained. Basalt is a typical example of extrusive igneous rocks.

The first three are sedimentary soils; quartzite is a metamorphic rock.

Availability of various rock forming elements (in percent) in earth’s crust (in % mass) is Oxygen – 46.6 Silicon – 27.7 Aluminium – 8.1 Iron – 5.0

Statement (1) is correct. Igneous rocks are the first one to be formed. All other rocks are formed by subsequent work of various rock forming processes and factors over these rocks. Thus, igneous rocks are also called parent rocks. Statement (2) is correct. Unlike sedimentary rocks, igneous rocks do not have any strata. Statement (4) is also correct. In the absence of pores in the igneous rocks, water does not penetrate in these rocks easily. Hence, igneous rocks are less affected by chemical weathering. Statement (3) is wrong. Sedimentary rocks are not the most widely distributed rocks on the earth’s surface.

Igneous rocks are divided into two main categories: plutonic rock and volcanic rock. Plutonic or intrusive rocks result when magma cools and crystallises slowly within the earth's crust. A common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta forming minerals such as pumice or basalt.

The scientific study of rocks is called petrology; pedology is the scientific study of soils.

Feldspars are a group of rock-forming tectosilicate (framework silicates) minerals that make up as much as 60% of the Earth's crust. Zeolites are framework silicates, with a completely linked framework of tetrahedra, each consisting of 4 O^2- surrounding a cation (usually Si⁴⁺ or Al³⁺).

It is correct.

Sandstone is a sedimentary rock composed of sand-sized mineral particles or rock fragments. It has significant porosity (typically 10-30%) and permeability due to the spaces between grains. In contrast, basalt, granite, and slate are much denser with very low porosity, making sandstone the most porous option.

Rocks are naturally occurring solid aggregates of minerals. Minerals are the homogenous substances (with definite chemical composition) that combine to form rocks. A single rock can contain one or multiple minerals.

Sedimentary rocks are formed from the accumulation of sediments in layers or beds over time. These layers often contain minerals that have settled out of water or air, leading to the occurrence of minerals in beds or layers. Examples include coal beds, iron ore bands, and limestone layers.