<span>Several
important pollutants are produced by fossil fuel combustion: carbon
monoxide, nitrogen oxides, sulfur oxides, and hydrocarbons. In addition,
total suspended particulates contribute to air pollution, and nitrogen
oxides and hydrocarbons can combine in the atmosphere to form
tropospheric ozone, the major constituent of smog.
Carbon monoxide is a gas formed as a by-product during the incomplete
combustion of all fossil fuels. Exposure to carbon monoxide can cause
headaches and place additional stress on people with heart disease. Cars
and trucks are the primary source of carbon monoxide emissions.
Two oxides of nitrogen--nitrogen dioxide and nitric oxide--are formed in
combustion. Nitrogen oxides appear as yellowish-brown clouds over many
city skylines. They can irritate the lungs, cause bronchitis and
pneumonia, and decrease resistance to respiratory infections. They also
lead to the formation of smog. The transportation sector is responsible
for close to half of the US emissions of nitrogen oxides; power plants
produce most of the rest.
Sulfur oxides are produced by the oxidization of the available sulfur in
a fuel. Utilities that use coal to generate electricity produce
two-thirds of the nation's sulfur dioxide emissions. Nitrogen oxides and
sulfur oxides are important constituents of acid rain. These gases
combine with water vapor in clouds to form sulfuric and nitric acids,
which become part of rain and snow. As the acids accumulate, lakes and
rivers become too acidic for plant and animal life. Acid rain also
affects crops and buildings.
Hydrocarbons are a broad class of pollutants made up of hundreds of
specific compounds containing carbon and hydrogen. The simplest
hydrocarbon, methane, does not readily react with nitrogen oxides to
form smog, but most other hydrocarbons do. Hydrocarbons are emitted from
human-made sources such as auto and truck exhaust, evaporation of
gasoline and solvents, and petroleum refining.
The white haze that can be seen over many cities is tropospheric ozone,
or smog. This gas is not emitted directly into the air; rather, it is
formed when ozone precursors mainly nonmethane hydrocarbons and nitrogen
oxides react in the presence of heat and sunlight. Human exposure to
ozone can produce shortness of breath and, over time, permanent lung
damage. Research shows that ozone may be harmful at levels even lower
than the current federal air standard. In addition, it can reduce crop
yields.
Finally, fossil fuel use also produces particulates, including dust,
soot, smoke, and other suspended matter, which are respiratory
irritants. In addition, particulates may contribute to acid rain
formation.
Also, water and land pollution.
</span>
Bears are omnivores (and scavengers), meaning they eat both plants and animals.
it can be both a primary consumer (if it eats plants) and secondary & tertiary consumers (if it eats a plant-eating animal). so it depends on what it eats.
Answer: The above statement is true
Explanation:
Mannitol salt agar is a medium which contain high concentration of salt,about 7.5%-10%. It is commonly used as a selective and differential growth medium.Because of its high concentration of salt,it inhibits growth if non halophiles(as they only grow best in media containing less tha 0.2M salts). If the bacteria can ferment mannitol,an acidic byproduct is formed which turns phenol red agar into yellow.So only those bacteria grow well which can ferment mannitol.
Taking into account the scientific notation, the result of the sum is 10.84300×10³.
- <u><em>Scientific notation</em></u>
First, remember that scientific notation is a quick way to represent a number using powers of base ten.
The numbers are written as a product:
a×10ⁿ
where:
- a is a real number greater than or equal to 1 and less than 10, to which a decimal point is added after the first digit if it is a non-integer number.
- n is an integer, which is called an exponent or an order of magnitude. Represents the number of times the comma is shifted. It is always an integer, positive if it is shifted to the left, negative if it is shifted to the right.
-
<u><em>Sum in scientific notation</em></u>
You want to add two numbers in scientific notation. It should be noted that when the numbers to be added do not have the same base 10 exponent, the base 10 power with the highest exponent must be found. In this case, the highest exponent is 3.
Then all the values are expressed as a function of the base 10 exponent with the highest exponent. In this case: 9.7300×10²= 0.97300×10³
Taking the quantities to the same exponent, all you have to do is add what was previously called the number "a". In this case:
0.97300×10³ + 9.8700×10³= (0.97300+ 9.8700)×10³= 10.84300×10³
Finally, the result of the sum is 10.84300×10³.
Learn more:
Elements in the same group tend to have very similar properties (D). This is due to the number of valence electrons each group has.
