Question

Which rock is also called the primary rock?
a)Igneous rock
b)Metamorphic rock
c)Sedimentary rock
d)None of these

Answer 1

Hint: An aggregate of one or more minerals is called rock. It's a naturally occurring substance that has a mixture of minerals fused together. There are three kinds of rocks-Igneous, metamorphic and sedimentary rocks.

Complete answer: A primary rock is a rock whose constituents are newly formed and have never been constituents of some other rock or formed through replacement and alterations. These are basically crystalline rocks with no organic remains on them.
Let us look at the options given to us
Option (A) igneous rock is correct as these are formed when hot magma cools down and solidifies. Igneous rocks are further classified into intrusive igneous rocks and extrusive igneous rocks. Intrusive or plutonic igneous rocks are formed when magma is trapped inside earth and cools down slowly over years forming coarse grained rocks.
Extrusive or volcanic igneous rocks are formed when magma cools down on or near Earth’s surface making fine grained rocks.
Option (B ) metamorphic rock is incorrect as metamorphic rocks are basically rocks which were previously sedimentary, igneous or some other metamorphic rocks but on application of pressure and heat has transformed into a new rock.
Option (C ) sedimentary rock is incorrect as sedimentary rocks are formed by the accumulation and cementation of organic matter and minerals.
Option (D ) This Option becomes irrelevant.

Thus, The correct answer is Option A.

Note: Examples of primary rock include granite, gneiss and schist.
Examples of sedimentary rock are sandstone, limestone and shales.
Examples of metamorphic rocks include marble and quartzite.