Direction: In this section, each item consists of six sentences of a passage. The first and the sixth sentences are given in the beginning as S1 and S6. The middle four sentences in each have been jumbled up and labelled as P, Q, R and S. You are required to find the proper sequence of the four sentences and mark your response accordingly on the Answer Sheet.

S1 : Nature can produce acidity in rains.
S6 : It can damage vegetation and wild life, corrode steel structures, bridges, buildings, statues, and harm human health too.
P : However, it is believed that the amount of acid produced in the atmosphere by nature is insignificant when compared to the amount produced from manmade sources.
Q : Lightening bolt can form oxides of nitrogen which in turn form nitric acid.
R : Recently it has been known that biological processes in the oceans are responsible for the production of Sulphuric acid.
S : Acid rain has made thousands of lakes fishless in Scandinavia, Canada and the United States.