Explanation:
Cumulonimbus clouds are a type of cumulus cloud associated with thunder storms and heavy precipitation. They are also a variation of nimbus or precipitation bearing clouds. They are formed beneath 20,000 ft. and are relatively close to the ground. ... These clouds often produce lightning in their heart.
Answer:
D. sulfur oxides from factories
Explanation:
This does not naturally occur, only if there is a factory. These other things happen on their own in nature but sulfur from factories relies on other factors down on earth.
Answer:
<em>The correct option is A) they are all classified as pure substances.</em>
Explanation:
Pure air is a term which is used to described air which is free from pollutants or other contaminants. All the substance from which air is made are considered as pure substances. Hence, option A is correct.
Other options, like option C, is false because the components of the air are no chemically bonded to one another. They exist freely. Options D is false because not all the components of air can be classified as an element. For example, carbon dioxide is not an element.