It should only be capitalized if it forms part of a title.
No it shouldn't be capitalized.
Earth, as in we live on the planet Earth, is supposed to be capitalized. Earth, as in the dirt we walk on, is not supposed to be capitalized.
Yes, Siamese would be capitalized.
No.
No it does not have to be capitalised.
No, it shouldn't be capitalized.
No it shouldn't be capitalized.
no
No, but the names of individual languages are capitalized.
no
Yes... indeed it is!
No, it is a common noun.
No it is a common noun.
Yes, the word "Americans" should be capitalized as it is a proper noun referring to the people of the United States of America.
No, but it is just one word: saltpeter.
No, except if the word is used at the beginning of a sentence.
Earth, as in we live on the planet Earth, is supposed to be capitalized. Earth, as in the dirt we walk on, is not supposed to be capitalized.