There are two accepted forms for possessive singular nouns ending in s:
Add an apostrophe s ('s) after the existing s at the end of the word.
Example: The atlas's cover is torn.
Add an apostrophe (') after the existing s at the end of the word.
Example: The atlas' cover is torn.
Atlas
The plural for the word atlas is atlases; the plural possessive is atlases'.
The possessive form of the singular noun neighbor is neighbor's.Example: My neighbor's garden is really beautiful.
The singular form for the plural noun countries is country; the singular possessive form is country's.
The singular possessive form for nation is nation's.example: Our nation's capital is Washington DC.
The explorer's sock (singular possessive) The explorers' socks (plural possessive)
The singular possessive form of "atlas" is "atlas's," pronounced as "at-luh-suhs."
The possessive singular of all English nouns, regardless of spelling, is formed by adding 's: atlas's ( pronounced "atlases" as if it were a plural).
When proper names end in an 's', it is common practice to create the possessive by simply adding an apostrophe without a further 's'. So, the strength of Atlas can be written as: Atlas' strength.
Quantum is singular, not singular possessive. The singular possessive form is quantum's.
The plural for the word atlas is atlases; the plural possessive is atlases'.
The plural for the word atlas is atlases; the plural possessive is atlases'.
Museum is singular. Museum's is singular possessive. Museums is plural. Museums' is plural possessive.
The singular possessive pronouns are "my," "mine," "your," "yours," "his," "her," and "its."
The singular possessive of dish is dish's
The singular possessive is Martin's.
The singular possessive is fish's.
Grave's is the singular possessive.