Noise & Radiation — Set 3
Environment · ध्वनि और विकिरण · Questions 21–30 of 40
Which of the following is considered the most hazardous level of continuous sound exposure for human health?
Correct Answer: D. 120 dB
Noise at 120 decibels is near the threshold of pain and can cause immediate hearing damage. Continuous exposure to such high levels leads to rapid permanent hearing loss. It is the intensity equivalent of a jet takeoff or a thunderclap nearby.
Cosmic radiation is a natural source of radiation that increases with?
Correct Answer: A. Altitude
At higher altitudes, there is less atmosphere to shield the earth from high-energy particles from space. Pilots and frequent flyers generally receive higher doses of cosmic radiation than people at sea level. This is a significant factor in evaluating radiation risks for space travel.
Which Indian law primarily regulates and controls noise pollution?
Correct Answer: C. The Environment (Protection) Act, 1986
The Noise Pollution Rules were framed in 2000 under the authority of the Environment (Protection) Act, 1986. This act gives the central government power to set standards for environmental quality. It provides the legal framework for local authorities to take action against noise violators.
Which type of radioactive decay involves the emission of a helium nucleus?
Correct Answer: D. Alpha decay
Alpha decay occurs when an unstable nucleus ejects a particle consisting of two protons and two neutrons. This particle is identical to a helium-4 nucleus. While they have low penetration power, alpha emitters are highly dangerous if inhaled or ingested.
The use of loudspeakers is generally prohibited between which hours in India?
Correct Answer: C. 10 PM to 6 AM
Loudspeakers are banned during the night from 10 PM to 6 AM to prevent sleep disturbance. This rule applies to both private and public spaces unless special permission is obtained for festivals. Courts have upheld this restriction as essential for the right to a peaceful life.
Which mineral is the primary source of radium and uranium in the earth's crust?
Correct Answer: D. Pitchblende
Pitchblende, also known as uraninite, is a radioactive, uranium-rich mineral. Marie Curie discovered radium and polonium by studying this specific ore. It is the most important mineral for the commercial extraction of radioactive elements.
What is the recommended limit for radiation exposure for a member of the general public per year?
Correct Answer: A. 1 mSv
The International Commission on Radiological Protection (ICRP) recommends a limit of 1 millisievert (mSv) per year for the public. This limit excludes natural background radiation and medical exposures. Higher limits are set for occupational workers who handle radioactive materials.
Which of the following noise-control methods is an example of 'Source Reduction'?
Correct Answer: D. Regular maintenance of machinery
The correct answer is 'Regular maintenance of machinery'. Source reduction focuses on preventing noise from being created in the first place. Oiling and repairing vibrating machine parts significantly lowers the sound level at the origin. It is generally the most effective way to manage industrial noise pollution.
Which radioactive isotope is commonly used in smoke detectors?
Correct Answer: D. Americium-241
Americium-241 is an alpha emitter used to ionize the air inside the detector's sensing chamber. When smoke particles enter, they disrupt this ionization, triggering the alarm. The amount of radioactive material used is extremely small and safe for household use.
What is the effect of 'Green Belts' (rows of trees) on noise pollution?
Correct Answer: B. They absorb and scatter sound
Trees and dense vegetation act as natural sound barriers by absorbing and deflecting sound waves. A wide belt of trees can significantly reduce the impact of highway noise on nearby residential areas. Broad-leaved evergreen trees are usually best for year-round noise reduction.