Harmful particles and gases in the air are known as

Pollutant

Explanation:

Any undesired particle that is present in the environment is known as pollutant. These can be particulate matter or harmful gases that is present in the atmosphere.

These gases can be carbon dioxide( more than normal), carbon monoxide, sulfur dioxide, et cetera. Pollutants can be pollen grains, dirt and smoke which pollutes the environment.

Hence, undesired particles are known as pollutants.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.