Questions

Weight of a person at a height of 2R from the centre of the earth, where R is the radius of the earth _______.

In the following question, the sentence given with blank to be filled in with an appropriate word. Select the correct alternative out of the fourand indicate it by selecting the appropriate option

She must ______ a great time at her birthday party.

A sentence has been given in Direct/Indirect Speech. Out of the four given alternatives, select the one which best expresses the same sentence in Indirect/Direct Speech
 
The lawyer said to them, “Call the witness."

Variation in human skin color is an example of

Which of the following cells produce antibodies?

Hormone that helps regulate calcium balance

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

Modern civilization is completely dependent on energy, which has therefore to be abundant and also economical. About 85% of the world's energy is supplied by oil, coal and natural gas while nuclear, hydro, wind and solar power and biomass supply the rest. Coal, nuclear and hydro are used primarily to generate electricity while natural gas is widely used for heating. Biomass is used both for heating and cooking. The wind and solar power is the future's hope as they are sustainable energy sources. Oil powers almost all machines that move and that makes oil uniquely versatile. Oil powered airplanes carry 500 people across the widest oceans at nearly the speed of sound. Oil powered machines produce and transport food. Oil powered machines are ubiquitous. Clearly, we live in the age of oil but it is drawing to a close. According to data available if oil production remains constant until it's gone, there is enough to last 42 years. Oil wells will produce less as they become depleted, which will make it impossible to keep production constant. Similarly natural gas and coal will last another 61 years and 133 years respectively. Naturally, as they become scarce, they become expensive, leading to a worldwide energy crisis. If we are to survive on this planet, we have to make a transition to sustainable energy sources. The transition may be willy-nilly or planned - the choice is ours.

The dawning era of limited and expensive energy will be very difficult for everyone on earth but will be even more difficult if it is not anticipated. It is of utmost importance that the public and policymakers understand the global energy crisis and act in tandem to ensure that the species 'homo sapiens' does not become extinct.

Biomass is an energy source used in

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.

What is crude mineral oil?