The thickness of ozone layer is? A. 25 to 50 km B. 3 km only C. 1 km only D. 25 to 28 km Right Answer: D. 25 to 28 km Share : December 13, 2017 Hassan Ali Chemistry Total 0 Votes: 0 0 Tell us how can we improve this Mcqs? Captcha: + = Verify Human or Spambot ? Related Mcqs Check Below -Elimination bimolecular reactions involve?Which one of the following has the maximum number of sp2 carbon atoms?1 gram formula refers to?