30. The atmospheric gas that is mainly responsible for green house effect : A.Ozone B.Nitrogen C.Oxygen D.Carbon dioxide
Answer: Option D Solution: Lemons, oranges, limes, and other citrus fruits naturally possess high concentrations of citric acid. The juice of the lemon is about 5% to 6% citric acid, which gives lemons a sour taste. In fact, Citric acid was first isolated in 1784 by the chemist Carl Wilhelm Scheele, who crystallized it from lemon juice.
