Question

1. as urban environments become denser, noise pollution is becoming a major environmental issue as people deal with noise generated from flight paths, freeways, work environments, and neighborhoods. which of the following is a true statement? (a) loud sound is not dangerous as long as you do not feel any pain in your ears. (b) hearing loss after sound exposure is temporary. (c) hearing loss is caused mostly by aging. (d) loud sound damages only your hearing. (e) if you have a hearing loss already, you still have to protect your hearing. 67. refer to the data below taken from a stream. the roman numerals indicate collection sites. where would the lowest do (dissolved oxygen) content be expected? (a) i (b) ii (c) iii (d) iv (e) dissolved oxygen would not be affected by sewage effluent. therefore, do would be equal at all points. 68. a certain pollutant has a concentration of 100 ppm in water. which statement most accurately describes this concentration? (a) out of 1,000,000 molecules of water, 100 would contain the pollutant. (b) there are 100 million molecules of pollutant in the water sample. (c) in one liter of water, there would be 100 million molecules of pollutant. (d) there are 100 molecules of pollutant in 999,900 molecules of water. (e) in 1 million liters of water, there would be 100 million molecules of pollutant.

Explanation:

Question 66:

Loud sounds can be dangerous even without ear - pain, hearing loss from sound exposure can be permanent, and it's not mainly caused by aging. Also, loud sound can have other health impacts besides on hearing. If one already has hearing loss, protecting remaining hearing is crucial.

Question 67:

Sewage effluent contains organic matter that is decomposed by bacteria, which consume dissolved oxygen. The area closest to the sewage discharge point (II) will have the lowest DO as the decomposition process starts immediately.

Question 68:

Parts - per - million (ppm) is a unit of concentration. 1 ppm means 1 part of a substance per million parts of the total mixture. So, 100 ppm means out of 1,000,000 molecules of the water - pollutant mixture, 100 are the pollutant.

Answer:

Question 66: E

Question 67: B

Question 68: A