Earth Science

Both Granite and Basalt are igneous rocks. Granite is an intrusive igneous rock formed from the slow cooling of magma beneath the Earth's surface, characterized by coarse grains of quartz, feldspar, and mica. Basalt is an extrusive igneous rock formed from the rapid cooling of lava at the surface, fine-grained and dark-colored, composed mainly of plagioclase and pyroxene. Sandstone and Limestone are sedimentary rocks, formed from compacted sand grains and calcium carbonate respectively. Since both Granite and Basalt are igneous, the question as originally posed is ambiguous if multiple answers are allowed. However, Basalt is a very common and classic example of an igneous rock, often used in such questions. Therefore, the best single answer to the question 'Which of the following is an igneous rock?' from the given options is Basalt (B).

Coal and petroleum are typically found in sedimentary rocks, which form from the accumulation of sediments and organic material over millions of years. These rocks provide the right conditions for the formation and preservation of fossil fuels.

Shale is a sedimentary rock, not a metamorphic rock. The other options—Slate, Schist, and Gneiss—are all types of metamorphic rocks formed from the alteration of pre-existing rocks under heat and pressure.

Precipitation refers to water that falls from the atmosphere to the Earth's surface, such as rain, snow, sleet, and hail. Fog is not precipitation because it consists of tiny water droplets suspended in the air near the ground rather than falling from clouds.

The question asks for the current era in the Geological Time Scale. The current era is the Cenozoic Era, which began about 66 million years ago and continues to the present. The Holocene is an epoch within the Quaternary Period of the Cenozoic Era, not an era itself. Since the options given are Paleozoic, Mesozoic, Holocene, and None of these, the correct answer is 'None of these' because the correct era (Cenozoic) is not listed among the options.

The term 'nife' comes from the combination of Nickel (Ni) and Iron (Fe), which are the primary components of the Earth's core. 'Ferrous' refers to iron-containing compounds, so option A correctly identifies the core's composition.

The Earth's crust is the thinnest layer compared to the mantle and core. It forms the outermost solid shell of the planet.

A Stevenson screen is a shelter used to house meteorological instruments such as wet bulb, maximum, and ordinary thermometers to protect them from direct sunlight and precipitation. An anemometer, which measures wind speed, is not housed inside a Stevenson screen.

Marble, Slate, and Gneiss are all types of metamorphic rocks. Quartzite is also a metamorphic rock, making it the most similar option. Limestone is sedimentary, Coal is organic sedimentary, and Sandstone is clastic sedimentary, so they are less similar.

Sandstone, limestone, and coal are all types of sedimentary rocks formed by the accumulation and compaction of sediments or organic materials over time. This makes option D the correct analogy.