Which of the following is an oxidation-reduction reaction? fe2o3 + 3co mc009-1.jpg 2fe + 3co2 cuso4 + 2naoh mc009-2.jpg cu(oh)2 + na2so4 2naoh + h2co3 mc009-3.jpg na2co3 + 2naoh pb(no3)2 + na2so4 mc009-4.jpg 2nano3 + pbso4

is an oxidation-reduction reaction.

Explanation:

In an oxidation-reduction reaction, the oxidation number of some elements must change during reaction.

represents an oxidation-reduction reaction.

                                                                    oxidation number

                             Fe in                       +3

                    Fe in Fe                                                        0

                    C in CO                                                        +2

                                C in                                  +4

SO, oxidation number of Fe decreases during reaction. Hence is being reduced. Also, oxidation number of C increases during reaction. Hence CO is being oxidized.

In all other given reactions, oxidation number of elements are not changed during reaction. Hence they are not oxidation-reduction reaction.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.

i just calculated it all out, and not including weekends, and all the different days off. as of this school year (2018-2019) students are spending 2198 hours in school this year