Почему реализация системы координат через положения квазаров точнее реализации через положения звезд?

Потому, что даже ближайшие квазары находятся значительно дальше звезд. Звезды принадлежат нашей Галактике. И расстояние до самой далекой из них не превышает 100000 св. лет.  Ближайший квазар расположен на расстоянии 600000000 св. лет. Таким образом параллакс даже самой далекой звезды будет в 6000 раз больше параллакса ближайшего квазара.  Следовательно и погрешность координат, реализованных через положение квазара, будет меньше.

1 дм² = 100 см²

12 000 см²  и  12 дм²

12 дм² = 12 * 100 = 1 200 см²     ⇒   12 000 см² > 12 дм²

1 км = 1 000 м

12 км  и  1 200 м:

12 км = 12 * 1 000 = 12 000 м    ⇒    12 км > 1 200 м

1 дм³ = 1 000 см³

12 000 см³  и  12 дм³:

12 дм³ = 12 * 1 000 = 12 000 см³    ⇒   12 000 см³ = 12 дм³

1 дм = 100 мм

12 000 мм  и  1 200 дм:

1 200 дм = 1 200 * 100 = 120 000 мм    ⇒    12 000 мм < 1 200 дм

1 т = 1 000 кг;   1 ц = 100 кг

1 т 2 ц  и  1 200 кг:

1 т 2 ц = 1 * 1 000 + 2 * 100 = 1 200 кг   ⇒    1 т 2 ц = 1 200 кг

A rain in which the precipitation is unusually acidic is called an acid rain. It contains high levels of hydrogen ions. Acid rain is caused when sulphur dioxide and nitrogen dioxide emissions react with water molecules in the air and result in producing acids. These chemicals are produced because of natural sources like decay of vegetation, volcanoes and also from manmade sources like emissions from factories and various types of pollution in the atmosphere. When these gases react with water that is present in the air, form into various acidic compositions.
Acid rains are very harmful to the atmosphere. Steel structures like bridges and towers corrode because of the acid. It also results in the peeling of paint from the painted surfaces like buildings. Stone structures get eroded because of the acid in the rain. 
Acid rain shows adverse effects on human health, forests, sources of fresh water like rivers and streams, and on soil affecting different life forms surviving in these mediums. 
What Is Smog?The term smog was first coined during the 1950s when it was used to describe a mixture of smoke and fog experienced in London. Major cities along the west coast of America were also experiencing a different type of air pollution.Smog occurs when emissions from industry, motor vehicles, incinerators, open burning and other sources accumulate under certain climatic conditions. There are two types of smog: summer (the type of smog first experienced in America) and winter (the one first noticed in London).Autumn And Winter Smog (Particles)During the cooler months (April to September), Melbourne is more affected by the accumulation of fine particles, which come from motor vehicle emissions, wood smoke, other combustion processes and photochemical processes in the air.Temperature inversions in winter mean that warm air higher in the atmosphere traps pollutants in the layer of cold air closer to the ground. These inversions can last for several days and cause 'scummy' brown hazed horizons until dispersed by wind or rain.The fine particles scatter sunlight, reduce visibility, soil buildings and fabrics and provoke existing respiratory diseases and other health problems.Photochemical Or Summer SmogIn the warmer months (October to March), photochemical smog (summer smog) is caused by the action of sunlight on a mixture of hydrocarbons and oxides of nitrogen. This smog contains secondary pollutants such as ozone, aldehydes and fine particles.