Question

Assertion : Methane component of green house gases contributing to global warming is about 20 percent.

Reason : Introduction of multi-point fuel injection engines in automobiles has decreased methane content in the exhausts.

(a) Both A and R are true and R is the correct explanation of A  

(b) Both A and R are true but R is not correct explanation of A  

(c) A is true but R is false  

(d) A and R are false

Answer 1

Correct option (b) 

Explanation :

Methane is largely a product of incomplete decomposition and is produced by a group of bacteria called methanogens under anaerobic conditions. The major sources of methane include freshwater wetlands, enteric fermentation in cattle and flooded rice fields. Biomass burning also produces methane. Major gases contributing in greenhouse effect with their percentage contribution are given in the given pie chart. Efficient engine (for example, multi point fuel injection engine) can reduce the unburnt carbons (like methane etc.) in auto emission.