The process of denitrification involves the reduction of nitrates (NO3-) to produce nitrogen gas (N2). Typically, this is facilitated by bacteria in anaerobic conditions. For the question of which reaction fits the description of denitrification, we need to examine the options provided:
a) [tex]\( NH_{4}^{+} + 1.5 \, O_{2} \rightarrow NO_{2}^{+} + H_{2}O + 2 \, H^{+} \)[/tex]
This reaction describes the oxidation of ammonium (NH4+) to nitrite (NO2-), which is not a reduction process characteristic of denitrification.
b) [tex]\( NO_{2} + 0.5 \, O_{2} \rightarrow NO_{3} \)[/tex]
This reaction describes the oxidation of nitrite (NO2-) to nitrate (NO3-), which is also not a reduction process, and thus not denitrification.
c) [tex]\( 5 \, C_{6}H_{12}O_{6} + 24 \, NO_{3} \rightarrow 24 \, HCO_{3}^{-} + 6 \, CO_{2} + 18 \, H_{2}O + 12 \, N_{2} \)[/tex]
This reaction describes the reduction of nitrate (NO3-) to nitrogen gas (N2) along with the formation of bicarbonate ions (HCO3-), carbon dioxide (CO2), and water (H2O). This is consistent with the denitrification process.
d) [tex]\( C_{6}H_{12}O_{6} + 6 \, O_{2} \rightarrow 6 \, CO_{2} + 6 \, H_{2}O \)[/tex]
This reaction describes the complete oxidation of glucose (C6H12O6) to carbon dioxide (CO2) and water (H2O), which occurs in aerobic conditions and is not related to denitrification.
Upon careful analysis of these reactions, the correct reaction that describes the process of denitrification is:
c) [tex]\( 5 \, C_{6}H_{12}O_{6} + 24 \, NO_{3}^{-} \rightarrow 24 \, HCO_{3}^{-} + 6 \, CO_{2} + 18 \, H_{2}O + 12 \, N_{2} \)[/tex]
