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Reading Passage
Crude mineral oil comes out of the earth as a thick brown or black liquid with a strong smell. It is a complex mixture of many different substances, each with its own individual qualities. Most of them are combinations of hydrogen and carbon in varying proportions. Such hydrocarbons are also found in other forms such as bitumen, asphalt and natural gas. Mineral oil originates from the carcasses of tiny animals and from plants that live in the sea. Over millions of years, these dead creatures form large deposits under the sea-bed; and ocean currents cover them with a blanket of sand and silt. As this mineral hardens, it becomes sedimentary rock and effectively shuts out the oxygen, so preventing the complete decomposition of the marine deposit's underneath. The layers of sedimentary rock become thicker and heavier. Their pressure produces heat, which transforms the tiny carcasses into crude oil in a process that is still going on today.

Mineral oil deposits under the sea do not get completely decomposed because they

20132Mprelimsupscyear-2013p2csatreading-comprehension
A.are constantly washed by the ocean currents
B.become rock and prevent oxygen from entering themCorrect
C.contain a mixture of hydrogen and carbon
D.are carcasses of organisms lying in saline conditions
Explanation & Solution

Correct Option: (B) become rock and prevent oxygen from entering them

According to the passage, when mineral deposits are covered by sedimentary rock, it 'effectively shuts out the oxygen, so preventing the complete decomposition'

हिंदी में प्रश्न एवं आदर्श उत्तर

पठित परिच्छेद
Crude mineral oil comes out of the earth as a thick brown or black liquid with a strong smell. It is a complex mixture of many different substances, each with its own individual qualities. Most of them are combinations of hydrogen and carbon in varying proportions. Such hydrocarbons are also found in other forms such as bitumen, asphalt and natural gas. Mineral oil originates from the carcasses of tiny animals and from plants that live in the sea. Over millions of years, these dead creatures form large deposits under the sea-bed; and ocean currents cover them with a blanket of sand and silt. As this mineral hardens, it becomes sedimentary rock and effectively shuts out the oxygen, so preventing the complete decomposition of the marine deposit's underneath. The layers of sedimentary rock become thicker and heavier. Their pressure produces heat, which transforms the tiny carcasses into crude oil in a process that is still going on today.

Mineral oil deposits under the sea do not get completely decomposed because they

A.are constantly washed by the ocean currents
B.become rock and prevent oxygen from entering themसही
C.contain a mixture of hydrogen and carbon
D.are carcasses of organisms lying in saline conditions

सही उत्तर: (B) become rock and prevent oxygen from entering them

According to the passage, when mineral deposits are covered by sedimentary rock, it 'effectively shuts out the oxygen, so preventing the complete decomposition'

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