No, you don’t, unless using the names as formal labels. They are scientific names, but not considered proper nouns.
Not unless it's the first word of a sentence. It is a common noun.
The full name of the element does not need to be capitalized, unless there is some independent grammatical reason for capitalization such as being in a title or the first word of a sentence. Thee chemical symbol for phosphorus, however, should be the single capital letter P.
It depends on where you put it in a sentence. Of coarse in the beginning of a sentence you capitalize space but by it's self no you don't capitalize.
The troposphere is the lowest layer of the atmosphere.
We live in the troposphere. The troposphere is under the stratosphere.
No. The separate levels of the atmosphere are not capitalized.
In general, no, "transition process" should not be capitalized in a sentence.
No, the word forecast should not be capitalized in a sentence.
Yes, "PC" should be capitalized in a sentence.
Yes it should be capitalized.
No, "secondary students" should not be capitalized in the middle of a sentence unless it is a proper noun or at the beginning of a sentence.
No, the word "fifteen" should not be capitalized in a date within a sentence unless it is the first word of the sentence.
Mammogram should not be capitalized unless it's the first word in the sentence.
Have should be capitalized if it is the beginning of a sentence. Summer should not be capitalized.
No, "methamphetamine" should not be capitalized unless it is at the beginning of a sentence.
Since 'felon' is a common noun, it is only capitalized if it is at the start of a sentence.
No it shouldn't be capitalized.