The possessive form of the singular noun shopper shows that something belongs to one person who is purchasing items in a store, on-line, marketplace, etc.
Example: The shopper's card was maxed out.
The singular possessive form is word's, for example the word's definition.
Quantum is singular, not singular possessive. The singular possessive form is quantum's.
The singular possessive of "ant" is "ant's" and the plural possessive is "ants'".
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
Grave's is the singular possessive.
The singular possessive form of "test" is "test's".
The singular possessive is Martin's.
The singular possessive is fish's.
Buzz's is the singular possessive.
The singular possessive is biker's; the plural possessive is bikers'.