General Knowledge - General Science - Discussion

Because all other options are gas only.

I actually think its A because oxygen usually causes things to rust l8k at the places with a lot of oxygen in the atmosphere.

I can't understand, I think it's either A or B, I'm not sure about my answer.

But why can't it be nitrogen?

Because when oxygen reacts with hydrogen chloride its get discolored.

Why brass gets discolored when it reacts hydrogen sulphide?

Hydrogen sulfide is a reducing agent and when brass comes in its contact reduction occurs and causes it discoloration being reactive and due to its acidic properties and oxygen and carbon dioxide can't do it. And it not present in dry air composition.

But you should not forget that some gases are present as pollutants and hydrogen sulphide is a primary pollutant and you cannot consider that the composition is always the same as it is described in books as pollutants are not considered while giving composition of dry air and more over moisture is there in air which helps in reduction of brass. As far as I understand and option B is the right option.

Should it be oxygen?

Why not carbon-dioxide is correct answer?

What is the disadvantage of nitrogen?