Q: Choose the correct statement.

Technically speaking, the sun is, in fact, not a source of inexhaustible energy, since every star eventually burns out. However, the sun's internal fuel supply will keep it burning for at least six billion years, enough to be considered inexhaustible for all practical purposes. The sun's nuclear furnace provides as much as 174 petawatts of solar energy to the planet, approximately 70 percent of which is absorbed by the surface.

Question 1

Which one of the following is not important for individual health?

Accepted Answer

Living in a large and well-furnished house is not guaranteed healthy living. In fact, people living in large, well-furnished houses have been seen frequently suffering from common lifestyle diseases like obesity, high blood pressure, diabetes, etc. Other ailments like allergies, poor mental health, lack of social life, etc. Maintaining a healthy lifestyle, consuming a balanced diet, regular exercises and having a proper social life is a key to good health. So, option D is correct

Question 2

It you live in an overcrowded and poorly ventilated house, it is possible that you may suffer from which of the following diseases?

Accepted Answer

If you live in an overcrowded and poorly ventilated house, it is possible that you may suffer from some air borne diseases. The chances of spreading the air borne diseases are more in the crowded and poorly ventilated area. This is because, in such areas, the person infected with some disease easily spreads the infectious droplets through breathing and sneezing. These infected droplets are inhaled by the healthy person who can become infected. In addition, if the house is not properly ventilated, the infectious droplets keep on circulating in the closed area and hence more and more people can become infected with the disease.

Question 3

Which of the following is a disadvantage of most of the renewable energy sources?

Accepted Answer

Energy- abundant, versatile, reliable, portable, and affordable, fossil fuels provide over 80 percent of the worlds energy because they are superior to the current alternatives, Disadvantage of most of the renewable energy sources is its unreliable supply. But to renewable energy resources from wind, solar, and biomass, man can control access to and conversion of the energy held in fossil fuels. Any machine or person can't control when the wind blows or at what velocity. No one can control how much of the radiant heat of the sun will hit the earth on a given day or hour.

Question 4

A substance which produces a lot of heat on burning is called:

Accepted Answer

A fuel is any material that can be made to react with other&#10;substances so that it releases chemical or nuclear energy as heat or to be used&#10;for work. The heat energy released by reactions of fuels is converted into&#10;mechanical energy via a heat engine. Other times the heat itself is valued for&#10;warmth, cooking, or industrial processes, as well as the illumination that&#10;comes with combustion.

Question 5

Commercial Sources of Energy are _________.

Accepted Answer

Coal, petroleum, water, and electricity are sources of commercial energy, which have price and consumer has to pay price to purchase them.The other examples of commercial sources of energy are fossil fuels, hydropower and nuclear energy.

Question 6

State whether the following statements are True or False.National highways connect large cities.

Accepted Answer

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Question 7

Which one of the following forms of energy leads to least environmental pollution in the process of its harnessing and utilization?

Accepted Answer

Solar energy is the energy that is in sunlight. It has been&#10;used for thousands of years in many different ways by people all over the&#10;world. As well as its traditional human uses in heating, cooking, and drying,&#10;it is used today to make electricity where other power supplies are absent,&#10;such as in remote places and in space. It is becoming cheaper to make&#10;electricity from solar energy and in many situations it is now competitive with&#10;energy from coal or oil. A solar cooker can be used for cooking food.&#10;&#10;Solar power plants convert sunlight into electricity, either&#10;directly using photovoltaics (PV), or indirectly using concentrated solar power&#10;(CSP). Concentrated solar power systems use lenses or mirrors and tracking&#10;systems to focus a large area of sunlight into a small beam. Photovoltaics&#10;converts light into electric current using the photoelectric effect. Thus there&#10;is no pollution associated with harnessing solar energy.

Question 8

Ocean thermal energy is due to __________.

Accepted Answer

Ocean Thermal Energy Conversion (OTEC) is a process that can&#10;produce electricity by using the temperature difference between deep cold ocean&#10;water and warm tropical surface waters. OTEC plants pump large quantities of&#10;deep cold seawater and surface seawater to run a power cycle and produce&#10;electricity.

Question 9

The energy which is not derived from the sun is:

Accepted Answer

Nuclear energy is released during nuclear fission and fusion. In nuclear fission, uranium atom is bombarded with low-energy neutrons. Hence, uranium atom splits into two relatively lighter nuclei. This reaction produces huge amount of energy.

Question 10

Choose the correct statement.

Accepted Answer

Technically speaking, the sun is,&#10;in fact, not a source of inexhaustible energy, since every star eventually&#10;burns out. However, the sun's internal fuel supply will keep it burning for at&#10;least six billion years, enough to be considered inexhaustible for all&#10;practical purposes. The sun's nuclear furnace provides as much as 174 petawatts&#10;of solar energy to the planet, approximately 70 percent of which is absorbed by&#10;the surface.