Chapter 16: Environmental Issues

Ans: Correct option is d.

The green scum found inside some water bodies includes both green algae and blue green algae in the scum. The excessive growth of such bloom-forming algae is fueled due to the presence of abundant nitrates and phosphates in the water body. These algal blooms grow excessively and then choke the water body. Green algae and blue-green algae both are photosynthetic and thus decrease the dissolved oxygen concentration of the water body. This decrease in oxygen kills flora and fauna of the water body. When microorganisms decompose algae using the oxygen in the water, it causes further reduction in the dissolved oxygen level and the aquatic life further depletes. 

Ans: Correct option is d.

A person can withstand about 80 dB loudness of a sound without a considerable discomfort. An individual person is capable of hearing as low as 0 dB at some times. Prolonged exposure of noise level above 80 dB can cause permanent loss of hearing or deafness. The tolerance to sound differs in different human beings and animals. 

Ans: Correct option is b

Transport system is a major contributor of noise pollution around the world. Transport has a substantial environmental impact as it is one of the largest energy consumers and burns the majority of the world's petroleum. This also leads to creation of nitrous oxides and particulates. Transport system is a very significant contributor to the increase in global warming due to excessive emissions of carbon dioxide. 

Ans: Correct option is a

i) The Environment protection act was established in 1986.

ii) The Air prevention and control of pollution act was established in 1981.

iii) The Water Act was enacted in 1974.

iv) The amendment of the air act to include noise as an air pollutant was done in 1987. 

Ans: Correct option is a

Catalytic converters are fitted in automobiles because they help in reducing emission of poisonous gases. Rhodium and platinum Palladium are some of the examples of catalysts commonly used in catalytic converters. Catalytic converters convert unburned hydrocarbons into carbon dioxide and water and carbon monoxide into CO2 gas which is less harmful and thus released. 

Ans: Correct option is a

SO2 can be reduced with the removal of sulphur from petrol and diesel exhaust emissions. SO2 is a fatal air pollutant; it can also damage the vegetation by causing chlorosis. It can also cause acid rain by forming H2SO3 in the atmosphere and such rain can damage buildings and plants. In human beings, acid rain can cause damage to the respiratory system, skin and irritation in eyes. 

Ans: Correct option is d

Suspended solids in water are the ones that are solid wastes including various impurities like sand, small stones, slit etc. These are heavy particles and thus get submerged at the bottom of water tanks and do not easily dissolve in water. Therefore, these can be easily and conveniently separated from water by various means like water filter, sedimentation, etc. 

Ans: Correct option is a

Hepatitis B is a viral infection which presents with symptoms like nausea, vomiting, fatigue and weakness. This infection can spread through sexual contact or from mother to foetus during pregnancy or lactation. So, the correct answer is option A. 

Ans: Correct option is d

Phosphorus in the form of phosphate and nitrates acts as nutrients or food for the algal blooms growing in water bodies. Increase in growth of algae due to addition of these pollutants leading to excessive algae nutrients in water bodies by humans is known as cultural eutrophication. It chokes the water body and leads to the death of aquatic flora and fauna. Decomposition of this algae and dead water organisms formed so further depletes dissolved oxygen content in water due to the microbes feeding on the matter. 

Ans: Correct option is a

Explanation: Algae blooms are the accelerated and excessive growth of blue green and green algae in a water body when environmental conditions allow explosive growth of phytoplankton that create dense clouds of these blooms which can even change the color of ocean water. All the photosynthetic phytoplankton have chlorophyll, the green pigment of photosynthesis, that explains why researchers measure chlorophyll concentrations to figure out how many phytoplankton are there in a certain region. Phytoplankton also have a few accessory pigments that allow them to use different wavelengths of sunlight for fulfilling their nourishment and cell growth needs.