It is best to say that most human sources of air pollution result from
a.
forestry management
b.
fuel burning
c.
heating devices
d.
vehicle exhaust

Answer : The correct option is, B.

Explanation :

Fuel burning : When the fuel burns, the carbon and hydrogen atoms combine with oxygen atoms to produce carbon dioxide and water vapor.

The burning of fuels like wood, coal and petroleum products releases unburnt carbon particles in the air. These unburnt carbon particles are the harmful pollutants which can cause respiratory diseases.

Therefore, the fuel burning is the human source of air pollution.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.