Read the passage and answer the questions:
Crude petroleum consists of hydrocarbons of liquid and gaseous states varying in chemical composition, color and specific gravity. It is an essential source of energy for all internal combustion engines in automobiles, railways and aircraft. Its numerous by-products are processed in petrochemical industries, such as fertilizer, synthetic rubber, synthetic fiber, medicines, vaseline, lubricants, wax, soap and cosmetics. Crude petroleum occurs in sedimentary rocks of the tertiary period. Oil exploration and production was systematically taken up after the Oil and Natural Gas Commission was set up in 1956. Till then, Digboi in Assam was the only oil producing region but the scenario changed after 1956. In recent years, new oil deposits have been found at the extreme western and eastern parts of the country. In Assam, Digboi, Naharkatiya and Moran are important oil producing areas. The major oilfields of Gujarat are Ankaleshwar, Kalol, Mehsana, Nawagam, Kosamba and Lunej. Mumbai High which lies 160 km off Mumbai was discovered in 1973 and production commenced in 1976. Oil and natural gas have been found in exploratory wells in Krishna-Godavari and Kaveri basin on the east coast. Oil extracted from the wells is crude oil and contains many impurities. It cannot be used directly. It needs to be refined. There are two types of refineries in India: (a) field-based and (b) market-based. Digboi is an example of field based and Barauni is an example of market based refinery.
Crude petroleum occurs in ________________ .
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → sedimentary rocks of tertiary period
Option (1) sedimentary rocks of tertiary period — Correct. Crude petroleum occurs in sedimentary rocks of the tertiary period.
Option (2) sedimentary rocks of pre-cambrian period — Incorrect. The rock type is right but the period is wrong: the Pre-Cambrian is the oldest part of the earth’s history, before about 540 million years ago.
Option (3) metamorphic rocks of tertiary period — Incorrect. The period is right but the rock type is wrong; metamorphic rocks are older rocks changed by heat and pressure.
Option (4) igneous rocks of cambrian period — Incorrect. Both parts are wrong: igneous rocks form from molten material, and the Cambrian is a very old period, about 540 to 485 million years ago.
Note: The concepts in Options (2) and (4), ‘pre-cambrian period’ and ‘cambrian period’, are not in NCERT (2025-26); explained here for the benefit of the students.
Note: A similar question was also asked in CUET (UG) 2023 on 05-06-2023 (Slot 1).
NCERT (2025-26): “Petroleum … Crude petroleum consists of hydrocarbons of liquid and gaseous states varying in chemical composition, colour and specific gravity. It is an essential source of energy for all internal combustion engines in automobiles, railways and aircraft. Its numerous by-products are processed in petrochemical industries, such as fertiliser, synthetic rubber, synthetic fibre, medicines, vaseline, lubricants, wax, soap and cosmetics.… Crude petroleum occurs in sedimentary rocks of the tertiary period. Oil exploration and production was systematically taken up after the Oil and Natural Gas Commission was set up in 1956. Till then, Digboi in Assam was the only oil producing region but the scenario changed after 1956. In recent years, new oil deposits have been found at the extreme western and eastern parts of the country. In Assam, Digboi, Naharkatiya and Moran are important oil producing areas.…” |