Ans. (a) The rocks formed deep inside the Earth as a result of the freezing of lava are called Plutonic rocks. These rocks are formed when magma cools and solidifies underground
Major plutonic rocks includes gabbro (dark in colour), diorite (an intermediate amount of silica), granite (68% silica) and pegmatite.

Ans. (b) Igneous rocks are referred to as primary rocks. These are the first rocks to originate during formation of the Earth’s crust. All other rocks are subsequently formed from igneous rocks through the process of sedimentation or metamorphosis.

Ans. (c) Igneous rocks are both crystal and non-crystal. Igneous rocks are formed by the cooling and solidification of magma or lava, which is molten or partially molten rock material.
Depending on the rate and conditions of cooling, igneous rocks can have different textures and compositions. Igneous rocks that cool slowly inside the Earth’s crust are called intrusive or plutonic rocks. They have large crystals that are usually visible without a microscope. This texture is known as Phaneritic. Examples of intrusive igneous rocks are granite, gabbro and diorite.

Ans. (a) Statement 1 is correct about the Igneous rock. Igneous rocks are formed by the cooling and solidification of molten rock (magma) from beneath the Earth crust. They are normally crystalline in structure.
Statements 2 and 3 are incorrect because they do not occur in strata nor do they contain fossils. Most igneous rocks contain silica between 45% to 70%. It ranges from lower silica basalt and gabbro to higher silica.

Ans. (d) All the statements are correct as the sedimentary rocks are formed at the Earth’s surface by the accumulation and lithification of sediment or by the precipitation from solution at normal surface temperatures. The hydrological systems such as rivers, running water plays a crucial role in formation of sedimentary rocks.
The formation of sedimentary rocks involves the weathering of pre-existing rocks. Weathering is the process of physical disintegration and chemical decomposition that occurs, when rocks at the Earth’s surface are exposed to the atmosphere and the hydrosphere.
All sedimentary rocks contain fossils. Fossils are the preserved remains or traces of ancient organisms that lived millions of years ago. Fossils are typically found in sedimentary rocks that are composed of organic or biogenic materials, such as limestone, coal and shale. Sedimentary rocks typically occur in layers. Layers are horizontal or nearly horizontal units of rock that have a distinctive appearance or composition from the rock above or below them.