Past Question on Acidity and NSW's Rainwater

[Aramy]

Question is from 2009, Question 8 Multiple Choice:
Unpolluted rainwater in New South Wales is slightly acidic. Which substance is the major contributor to this acidity?
a) Ozone
b) Sulfur Dioxide
c) Carbon Dioxide
d) Nitrogen Dioxide
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I was doing some past questions and looking through them and such, but I came across this one,
I assumed that Sulfur And Nitrogen were the distractions - because the question states "unpolluted" but i was more leaning towards Carbon Dioxide
being the correct one, cause it's a normal biological product from life, reacting with water to form Carbonic acid (decreasing pH), but the answer bank says it's Ozone.
Why so? What property of Ozone contributes to slightly acidic water?
Thanks! 

[hi.itsjessi]

Hi friend!

So basically, the reason I would say that it isnt nitrogen dioxide, carbon dioxide or sulfur dioxide is because of the fact that those 3 gases are actually pollutants and the question has specifically asked for unpolluted water! I can understand why you would think that it's carbon dioxide, but it's actually considered to be a pollutant!
As for the property of ozone in contributing to slight acidity, it reacts with water to produce hydrogen peroxide which is acidic

EDIT: I was a little confused when I saw the question too, especially because ozone and the affect it has on water isn't on the syllabus, so i assume that you're just meant to know that the 3 gases above are pollutants so it leaves you with ozone

Hope this helps!!