GK questions about earth's atmosphere for PA/SA Exam 2014

Earth's atmosphere

1. Which is the most abundant gas in earth's atmosphere  ?
answer: Nitrogen 


2. What is the percentage of oxygen in earth's atmosphere ?
answer: 21 % 


3. Which is the most abundant noble gas in earth's atmosphere ?
answer: Argon 

4. Which is the lower most layer in earth's atmosphere ?
answer: Troposphere 


5.  Weather phenomena like cloud, rain, snow, storm etc are formed in which atmospheric layer of earth ?
answer: Troposphere


6. In which atmospheric layer the phenomenon Aurora Borealis occurs ?
answer: Thermosphere