Human evolution known to be a process in which species adapt to certain
conditions of life, and in the battle of life and death, they are forced
to become stronger in order to survive in this world. Diseases have
always been present during the evolution, acting themselves as a natural
selectors - the weaker organisms get sick and die. Not just humans, but
all species have to establish a great protecting mechanism in order to
survive. That is how our bodies are built, to be able to withstand and
survive in the conditions we live in, and that is why our immune system
has to be taken care of.
Answer:
A
Explanation:
As it is caused by human intervention and doesn't occur naturally.
Fossil fuels are hydrocarbons, primarily coal, fuel oil or natural gas, formed from the remains of dead plants and animals.
In common dialogue, the term fossil fuel also includes hydrocarbon-containing natural resources that are not derived from animal or plant sources.
These are sometimes known instead as mineral fuels.
The utilization of fossil fuels has enabled large-scale industrial development and largely supplanted water-driven mills, as well as the combustion of wood or peat for heat.
Fossil fuel is a general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth's crust over hundreds of millions of years.
The burning of fossil fuels by humans is the largest source of emissions of carbon dioxide, which is one of the greenhouse gases that allows radiative forcing and contributes to global warming.
A small portion of hydrocarbon-based fuels are biofuels derived from atmospheric carbon dioxide, and thus do not increase the net amount of carbon dioxide in the atmosphere.
The phase contrast microscope uses out-of-phase and in-phase light rays that produce contrast areas allowing scientists to detect even a minute number of protein molecules and focus on the minute internal structures of a particle.
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The answer is 22.5 lb/gal.
The density of a liquid is quotient of mass and volume: D = m/V. The unit of the density is pound per gallon (lb/gal)
The density is unknown: D=?
But, we have:
mass: m= 90 lbs
volume: V = 4 gals
Do, the density of a liquid is:
D = 90 lbs / 4 gals
D = 22.5 lb/gal
