Give a reason for each of the following:

1. Igneous rocks are also called Primary rocks
2. Fossils are present in Sedimentary rocks
3. The core of the Earth is in a semi—solid state

1. Igneous rocks are also called primary rocks because they are formed when molten lava solidifies. Sedimentary rocks and metamorphic rocks are formed from other rocks.
2. Sedimentary rocks which are organically formed consist of remains or forms of sea plants and animals which have been buried and preserved in these rocks for a long time. They may have fossils trapped in their layers while formation of sedimentary rocks.
3. The core of the Earth is in a semi—solid state because of extreme pressure which is 3 million tonnes greater at core than at the surface.