CBSE Questions for Class 12 Medical Biology Environmental Issues Quiz 9 - MCQExams.com

The Kyshtym accident occurred in plutonium production site in Russia on 29 September 1957. It occurred due to uncontrolled heating of the radioactive liquid waste. Windscale fire accident occurred in 1957 in England in the nuclear reactor facility. The graphite reactor lost its coolant and as a result, the adjacent uranium cartridge started heating up. The leakage of the radioactive waves caused a massive fire incident that took almost 16 hours to control.

A. Windscale accident occurred on 10 October 1957.

B. The Church Rock Uranium mill accident occurred in 1979.

C. The Three Mile accident occurred in 1979.

D. The Kyshtym accident occurred on 29 September 1957

Svante Arrhenius, a Swedish scientist, in 1896 gave the theory related to the effects of the combustion-released carbon dioxide. He depicted the relation between the concentration of the carbon dioxide and the increase in temperature due to it. The greenhouse effect refers to the trapping of the infra-red rays reflected by the earth’s surface by the gases present in the troposphere. It is a natural process and is responsible for maintaining the survivable temperature in earth. However, anthropogenic release of the greenhouse gases has caused the events of global warming. Hence, the correct answer is 'Svante Arrhenius'.

• The Vienna Convention for the Protection of the Ozone Layer is a multilateral environmental agreement signed in 1985.
• It provided frameworks for international reductions in the production of chlorofluorocarbons due to their contribution to the destruction of the ozone layer and the resulting increase in the threat of skin cancer.
• The Number of ozone depleters identified by Viena convention for Protection of Ozone Layer (1992) is 19.
• So, the correct answer is '19'.

Air pollution is caused by the release of harmful oxides of nitrogen, sulphur and carbon from the vehicular exhausts and industrial emissions primarily. Using precipitators allow the removal of dust from these emissions. Keeping the air clean by minimizing the combustion of fossil fuels, less use of vehicles, use of catalytic converters can help in reducing the air pollution. Reusing waste allows the minimal production of non-degradable waste. Hence, the correct answer is 'Reusing wastes'.

• Electrostatic precipitator is used to remove particulate matter present in the air. The particulate matter are charged and passed through a chamber where they the particles lose their charge and settle down.
• Scrubbers are used to remove gases like sulphur dioxide (SO₂). The exhaust is passed though a spray of lime or water.
• Catalytic convertors consist of expensive metals like platinum- palladium and rhodium as catalysts which are fitted in the automobiles to reduce the emission of poisonous gases. When the exhaust passes through catalytic convertor, unburnt hydrocarbons get converted into carbon dioxide and water, carbon monoxide is converted to carbon dioxide and nitric oxide is converted to nitrogen gas.

• An electrostatic precipitator is a device that removes suspended dust particles from a gas or exhaust by applying a high-voltage electrostatic charge and collecting the particles on charged plates. It can remove 99% of particulate matter from thermal power plant exhaust.
• BOD(Biochemical oxygen demand) is a measure of, the amount of oxygen that require for the bacteria to degrade the organic components present in water/wastewater. Hence based on the BOD it is possible to estimate the amount of organic matter in sewage water.
  
• Hence b and c are correct statements.
• So, the correct answer is 'b and c correct'.

• Compressed natural gas (CNG) (methane stored at high pressure) is a fuel which can be used in place of gasoline, diesel fuel, and propane/LPG. 
• CNG combustion produces fewer undesirable gases than the aforementioned fuels.
• The main difficulty of was laying down pipelines for delivering CNG through distribution points up to the CNG pumps and to ensure uninterrupted supply.
• Hence it is difficult to lay down pipelines for delivery of CNG.
• So, the correct answer is 'Option E'.