Explanation:
(A)role of nittogen fixing bacteria
=Nitrogen-fixing bacteria, microorganisms capable of transforming atmospheric nitrogen into fixed nitrogen (inorganic compounds usable by plants). More than 90 percent of all nitrogen fixation is effected by these organisms, which thus play an important role in the nitrogen cycle.
B)role of nitrifying bacteria
=Nitrifying bacteria convert the most reduced form of soil nitrogen, ammonia, into its most oxidized form, nitrate. In itself, this is important for soil ecosystem function, in controlling losses of soil nitrogen through leaching and denitrification of nitrate.
C)role of denitrifying bacteria
=Denitrifying bacteria converts nitrates back to nitrogen gas.
There can only be two electrons in the innermost shell of an atom so b is the correct answer
Naming conventions for 2 non-metals like Si and O are based on their valence electrons, Si has 4 electrons around it and Oxygen has 6, in order for you to satisfy octet (8 electrons around each element) surrounding each Si and O, you need another O, To name these 2, just write the name of the first element which has less electrons first then the second element to which you use a prefix "di" since it means there are two oxygen, then put the names together and end the name of the second element with "ide" (remove the last 4 letters).
Silicon + "dI" + ox +"ide"