Questions

The Lachman test is used to evaluate stability of the

The credit for classifying the elements on the basis of their atomic masses goes to

Hirakud reservoir is built across the river

Matter is classified as a

In the following question, out of the four alternatives, select the alternative which will improve the bracketed part of the sentence. In case no improvement is needed, select "no improvement".
After they (had finished) eating they went for a walk.

In the following question, a sentence has been given in Direct/Indirect speech. Out of the four alternatives suggested, select the one which best expresses the same sentence in Indirect/Direct speech.

He said, "I had gone to my native place last month."

In the following question, a sentence has been given in Active/Passive voice. Out of the four alternatives suggested, select the one which best expresses the same sentence in Passive/Active voice.

The fire will burn this house.

Read the passage carefully and choose the best answer to each question out of the four alternatives and click the button corresponding to it.

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 million of years, these dead creatures form large deposits under sea­bed and ocean currents cover them with a blanket of sand and silt. As this material hardens, it becomes sedimentary rock and effectively shuts out the oxygen, thus preventing the complete decomposition of the marine deposits underneath. The layers of sedimentary rocks 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.

Sedimentary rocks leads to the formation of oil deposits because