Question

Choose the CORRECT match of sedimentary rocks in GROUP X with their processes/mechanisms of formation in GROUP Y.

GROUP X	GROUP Y
(P) Evaporite	(I) Physical process mainly consisting of lithification/cementation of deposition
(Q) Sandstone	(II) Chemical process and depositions by marine living organisms
(R) Limestone	(III) Anaerobic deposition of organic materials in mud bed
(S) Siltstone	(IV) Evaporation and precipitation of marine water

• A. P-IV; Q-I; R-II; S-III
• B. P-II; Q-IV; R-I; S-III
• C. P-II; Q-III; R-IV; S-I
• D. P-IV; Q-III; R-I; S-II

Hint:

Match each rock to its formation process: evaporite forms by evaporation, sandstone by physical cementation, limestone by marine biochemical processes, siltstone by anaerobic mud deposition.

Answer 1

The Correct Option is A

Step 1: Identify the formation process of Evaporite (P):
Evaporite rocks such as rock salt and gypsum form when marine or lake water evaporates over time, causing dissolved salts and minerals to precipitate out of solution. This matches process (IV), evaporation and precipitation of marine water. So P-IV.
Step 2: Identify the formation process of Sandstone (Q):
Sandstone is a clastic sedimentary rock formed mainly by the mechanical deposition of sand sized grains, which are then compacted and cemented together. This is a physical process of lithification and cementation of deposited grains, matching process (I). So Q-I.
Step 3: Identify the formation process of Limestone (R):
Limestone is largely a chemical and biochemical sedimentary rock, formed from the calcium carbonate skeletal remains of marine organisms such as corals, shells, and foraminifera, along with direct chemical precipitation of calcium carbonate from seawater. This matches process (II), chemical process and deposition by marine living organisms. So R-II.
Step 4: Identify the formation process of Siltstone (S):
Siltstone forms from fine silt sized sediment that settles in low energy, often oxygen poor (anaerobic) muddy environments, frequently along with organic material trapped in the fine mud bed. This matches process (III), anaerobic deposition of organic materials in a mud bed. So S-III.
Step 5: Combine all the matches:
P-IV, Q-I, R-II, S-III, which corresponds to option (A).
Final Answer:
\[ \boxed{\text{P-IV; Q-I; R-II; S-III}} \]