Class 10 General Science NCERT Based - 4 - Free MCQ Practice Test

• Hydro power plants convert the potential energy of falling water into electricity. In order to produce hydroelectricity, high-rise dams are constructed on the river to obstruct the flow of water and thereby collect water in larger reservoirs.

• The water level rises and in this process the kinetic energy of flowing water gets transformed into potential energy. But, constructions of big dams have certain problems associated with it.

• Large ecosystems get destroyed when submerged under the water in dams. The vegetation which is submerged, rots under anaerobic conditions and gives rise to large amounts of methane which is a greenhouse gas.

• Cow dung cakes serve as a steady source of fuel. Since, these fuels are derived from plants and animals hence they constitute – Biomass.

• These fuels, however, do not produce much heat on burning but a lot of smoke is given out when they are burnt. Cow-dung, various plant materials like crops residue, vegetable waste and sewage are decomposed in the absence of oxygen to give Biogas. Since the starting material is mainly cow-dung, it is popularly known as ‘gobar-gas’.

• Bio-gas is produced in a dome-shaped plant. Bio-gas is an excellent fuel as it contains up to 75% methane. It burns without smoke, leaves no residue like ash in wood, charcoal and coal burning. Its heating capacity is high.

• Solar cells convert solar energy into electricity. Silicon is used for making solar cells, which is abundant in nature, but availability of the special grade silicon for making solar cells is limited.

• The entire process of manufacture is still very expensive, silver used for interconnection of the cells in the panel further adds to the cost. The principal advantages associated with solar cells are that they have no moving parts, require little maintenance and work quite satisfactorily without the use of any focusing device.

• Another advantage is that they can be set up in remote and inaccessible hamlets or very sparsely inhabited areas in which laying of a power transmission line may be expensive and not commercially viable.

• The water at the surface of the sea or ocean is heated by the Sun while the water in deeper sections is relatively cold. This difference in temperature is exploited to obtain energy in ocean-thermal energy conversion plants.

• These plants can operate if the temperature difference between the water at the surface and water at depths up to 2 km is 293 K (20°C) or more. The warm surface-water is used to boil a volatile liquid like ammonia.

• The vapours of the liquid are then used to run the turbine of the generator. The cold water from the depth of the ocean is pumped up and condenses vapour again to liquid.

Statement 1: In nuclear fission, a heavy nucleus (like uranium-235 or plutonium-239) splits into two or more lighter nuclei, releasing a large amount of energy along with neutrons.
So, this statement is correct.

Statement 2: In a nuclear reactor used for power generation, the fission reaction is carefully controlled using control rods and moderators. This ensures that energy is released at a steady, manageable rate rather than explosively.
So, this statement is also correct.

Hence, the correct answer is Option C.

Nuclear power reactors located at Tarapur (Maharashtra), Rana Pratap Sagar (Rajasthan), Kalpakkam (Tamil Nadu), Narora (UP), Kakrapar (Gujarat) and Kaiga (Karnataka) have the installed capacity of less than 3% of the total electricity generation capacity of our country.

• Fusion means joining lighter nuclei to make a heavier nucleus, most commonly hydrogen isotopes are added together to create Helium. It releases a tremendous amount of energy, according to the Einstein equation, as the mass of the product is little less than the sum of the masses of the original individual nuclei.

• Such nuclear fusion reactions are the source of energy in the Sun and other stars. It takes considerable energy to force the nuclei to fuse. The conditions needed for this process are extreme – millions of degrees of temperature and millions of pascals of pressure.

• Organisms which can make organic compounds like sugar and starch from inorganic substances using the radiant energy of the Sun in the presence of chlorophyll are called the producers or autotrophs.

• All green plants and certain blue green algae which can produce food by photosynthesis come under this category. All fungi are heterotrophs, they use enzymes to break down the materials on which they are growing, fungi are largely responsible for organic decomposition, they are also capable of fermentation.

• The microorganisms, comprising Bacteria and Fungi, break-down the dead remains and waste products of organisms. These microorganisms are the decomposers as they break-down the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants.

• Food chain is the series of organisms feeding on one another. The food we eat acts as a fuel to provide us energy to do work.

• Thus the interactions among various components of the environment involves flow of energy from one component of the system to another. The length and complexity of food chains vary greatly.

• Each organism is generally eaten by two or more other kinds of organisms which in turn are eaten by several other organisms. So instead of a straight line food chain, the relationship can be shown as a series of branching lines called a food web.

• The autotrophs capture the energy present in sunlight and convert it into chemical energy which remains stored in the form of Carbohydrates.

• The flow of energy is unidirectional. The energy that is captured by the autotrophs does not revert back to the solar input and the energy which passes to the herbivores does not come back to autotrophs.

• As it moves progressively through the various trophic levels it is no longer available to the previous level. The green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight that falls on their leaves, rest gets dissipated.

• When green plants are eaten by primary consumers, a great deal of energy is lost as heat to the environment, some amount goes into digestion and in doing work and the rest goes towards growth and reproduction.

• An average of 10% of the food eaten is turned into its own body and made available for the next level of consumers.Therefore, 10% can be taken as the average value for the amount of organic matter that is present at each step and reaches the next level of consumers.

• The chemicals which are used to protect the crops from pests are either washed down into the soil or into the water bodies. From the soil, these are absorbed by the plants along with water and minerals, and from the water bodies these are taken up by aquatic plants and animals. Thus they enter the food chain. As these chemicals are not degradable, these get accumulated progressively at each trophic level.

• As Human beings occupy the top level in any food chain, the maximum concentration of these chemicals get accumulated in our bodies. This phenomenon is known as Biological Magnification.

• Ozone (O₃) is a molecule formed by three atoms of oxygen. Ozone is a deadly poison.

• However, at the higher levels of the atmosphere, ozone performs an essential function. It shields the surface of the earth from ultraviolet (UV) radiation from the Sun. This radiation is highly damaging to organisms, for example, it is known to cause skin cancer in human beings.

• The amount of ozone in the atmosphere began to drop sharply in the 1980s. This decrease has been linked to synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers. In 1987, the United Nations Environment Programme (UNEP) succeeded in forging an agreement to freeze CFC production at 1986 levels.

• Hydrogen bomb is based on the 'nuclear fusion' technology. In order to release more energy, atoms have been fused together in the making of H-Bomb.Hydrogen Bombs use fusion, the same way that powers the Sun or any other star.

• Isotopes of hydrogen are forced together to release a much bigger blast — hundred times powerful than the nuclear weapon that has been used in warfare.

• The Ganga Action Plan was a multi-crore project which came about in 1985 because the quality of the water in the Ganga was very poor. The Ganga runs its course of over 2500 km from Gangotri in the Himalayas to Ganga Sagar in the Bay of Bengal.

• It is being turned into a drain by more than a hundred towns and cities in Uttar Pradesh, Bihar and West Bengal that pour their garbage and excreta into it. Largely untreated sewage is dumped into the Ganges every day.

• In addition, pollution is caused by other human activities like bathing, washing of clothes and immersion of ashes or unburnt corpses. And then, industries contribute chemical effluents to the Ganga pollution load and the toxicity kills fish in large sections of the river.

The Government of India instituted an ‘Amrita Devi Bishnoi National Award for Wildlife Conservation’ in the memory of Amrita Devi Bishnoi, who in 1731 sacrificed her life along with 363 others for the protection of ‘khejri’ trees in Khejarli village near Jodhpur in Rajasthan.

• The Sustainable Development Goals agenda was accepted by all members of the United Nations in 2012 at the Rio De Janeiro Council Meet with an aim to promote a healthy and developed future of the planet and its people.

• It was in 2015 when the Sustainable Development Goals were implemented after a successful fifteen-year plan of development called the Millennium Development Goals. It is a group of 17 goals with 169 targets and 304 indicators, as proposed by the United Nation General Assembly’s Open Working Group on Sustainable Development Goals to be achieved by 2030.

• Post negotiations, an agenda titled “Transforming Our World: the 2030 agenda for Sustainable Development” was adopted at the United Nations Sustainable Development Summit. SDGs is the outcome of the Rio+20 conference (2012) held in Rio De Janeiro and is a non-binding document.