"Mars", as in the name of the Roman God of War, or the name of the planet, or the name of the candy company, is a proper noun and should be capitalized.
"Park Avenue" is a proper noun, because it is a place. Proper nouns like this should always be capitalized.
Common
It is a proper noun, because it is the name of a specific thing.
proper
Proper noun
When used as the name of a planet , it is a proper noun , and should be spelt with a capital 'M' , wherever it appears in the sentence. So your question should read, 'Is Mars a common noun or a proper noun?'
"Park Avenue" is a proper noun, because it is a place. Proper nouns like this should always be capitalized.
Yes The noun Mars Bar is a proper noun, the name of a specific product. A proper noun is always capitalized.
A proper noun is the name of a specific person, place, or thing. The proper noun for the common noun planet is the name of a planet, for example Venus, Mars, Earth, Pluto, etc.
Common
It is a proper noun, because it is the name of a specific thing.
proper
Proper noun
Pencil proper or common noun
it's a common noun. a proper noun would be Spider-Man.
Proper noun or common noun
The noun cassette is a common noun.