Questions

(a) refers to political importance and (b) to economic importance. Out of (c) and (d), (c) is more important.

QUEUE is the only word with 5 letters but sounds like one letter 'Q'.

Carbon monoxide is one of the major pollutant present in the world. The six most common pollutants include ozone, carbon monoxide, sulfur dioxide, lead, nitrogen oxides, and particulate matter.

Carbon monoxide is a common atmospheric pollutant. It is produced largely in combustion processes like in industries and in vehicles. It is a gas that cannot be seen nor smelled.

Mutations are accidents in the copying of DNA. A genetic mutation is a random change in the DNA that is passed on further generations of cells and or organisms. 

Genetic mutations are accidental changes in the DNA in the germ cells or early in the formation of the embryo. These changes if they are in the germ cell will be passed on to other organisms formed by sexual reproduction or asexual reproduction. An example would be the golden delicious apple. A lost of genetic information due to a mutation resulted in a different color of fruit.

Genetic mutations that cause diseases are not always passed on to offspring.