Rocks and Earth Materials

The near horizontal bodies of the intrusive igneous rocks are called sill or sheet. The thinner ones are called sheets while the thick horizontal deposits are called sills.

Half of the earth’s crust is composed of feldspar.

Igneous rocks — solidified from magma and lava Granite, gabbro, pegmatite, basalt, volcanic breccia and tuff are some of the examples of igneous rocks.

In this question, A statement speaks about 'fairly soft'. So, the next statement should be in relation to it. D statement correctly follows A. It is so soft that it can even be dissolved by weak acids. Now, the next statement should about acid. D introduces 'acid' and B tells the source of acid, so, DB is also the key. This means ADB sequence is the most logical one. Option (3) which has CADB is the answer.

Their bases were usually convex, so that they could be set in the earth or in the mud to prevent their rocking.

Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. In general, the composition of lava determines its behaviour more than the temperature of its eruption. Acid lava comes from composite cone volcanoes, is slow moving and viscous. Basic lava comes from shield volcanoes, is runny and flows faster. Acidic lava is felsic, or high in quartz and potassium feldspars. Basic lava is mafic and higher in plagioclase feldspar.

Acid rain corrodes marbles of a monument. This phenomenon is called marble cancer.

Quartzite is a metamorphic rock formed from sandstone when the quartz grains recrystallize under heat and pressure, creating a hard, interlocking crystal structure. The transformation eliminates the original sedimentary texture while maintaining the chemical composition.

Two names for a magnetic rock are load stone and magnetite.

Quartzite is the metamorphic rock formed from sandstone. Under intense heat and pressure, the quartz grains in sandstone recrystallize to form quartzite, a much harder and more compact rock. Marble is the metamorphic form of limestone, gneiss can form from various rocks depending on composition, and granite is an igneous rock, not metamorphic.

An example of a sedimentary cycle is phosphorous cycle.

Option 2 is the correct answer.

Marble is a metamorphic rock formed from limestone under heat and pressure. Both marble and limestone are primarily composed of calcium carbonate (CaCO3). The metamorphic process recrystallizes the calcite in limestone, giving marble its characteristic crystalline structure. Graphite and coal are carbon-based, while basalt is an igneous rock.

Edward Suess classified Earth's interior into three compositional layers: Sial (silica + aluminum, the upper continental crust), Sima (silica + magnesium, the oceanic crust and lower continental crust), and Nife (nickel + iron, the core). Mohorovicic discovered the Moho discontinuity, Gutenberg discovered the core-mantle boundary, and Connard identified the Conrad discontinuity within the crust.

Silicon (28%) and oxygen (46%) are the two most abundant elements in Earth's crust by mass, combined primarily as silicates and silica. Together they account for about 75% of the crust's composition. Nitrogen is mainly in the atmosphere, while carbon is present but not in crustal abundance.