Q1. In which type of rocks, fossils are more abundantly found ?
(a) Igneous
(b) Metamorphic
(c) Sedimentary
(d) None of these
(UPSC Prelims 1982)
Answer: (c) Sedimentary
Explanation: Sedimentary rocks form from layers of deposited material, often preserving organic remains, making them the primary source of fossils.
Q2. Generally speaking, all rocks may be classified into three major groups, such as
(a) Marble, limestone, igneous
(b) Igneous, limestone, mica
(c) Igneous, marble, sedimentary
(d) Igneous, sedimentary and metamorphic
(UPSC Prelims 1982)
Answer: (d)
Explanation:
Rocks are broadly classified into three types:
- Igneous (formed from molten magma)
- Sedimentary (formed from deposition of particles)
- Metamorphic (formed by transformation under heat and pressure)
- This classification is based on their origin and formation process.
Q3. Extrusive (Intrusive) rocks are forms of
(a) Igneous rocks
(b) Sedimentary rocks
(c) Metamorphic rocks
(d) None of the above
Answer: (a) Igneous rocks
Explanation:
Extrusive and intrusive rocks are types of igneous rocks.
- Extrusive: formed from lava cooling on the surface (e.g., basalt)
- Intrusive: formed from magma cooling beneath the surface (e.g., granite)
- They originate from volcanic activity.
Q4. Which of the following terms is used to denote the heavy rocks of the lithosphere?
(a) Substratum
(b) SIAL
(c) SIMA
(d) None of the above
(UPSC Prelims 1986)
Answer: (c) SIMA
Explanation: SIMA refers to the lower layer of the Earth’s crust, composed mainly of silica and magnesium, and is denser and heavier than the upper layer SIAL (silica and aluminium). It forms the oceanic crust and deeper lithosphere.
