High diagram shows the valence electron pattern for a carbon atom

The right answer is A.

The carbon having 6 electrons adopts an electronic configuration in the ground state 1s2 2s2 2p2. It has four electrons on its valence layer, which allows it to form four covalent bonds, including "sigma" (first bond with one atom) or "pi" type bonds (second or third bond). "Pi" type links are always accompanied by a "sigma" type link. The recovery of electronic functions in a "pi" link is weaker. These links are therefore less "solid".

1.the evidene of the reaction

2.yes

3.yes

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.