Answer:
When something is vague, it is not being specific but when something is ambiguous, it has multiple meanings and so can be open to interpretation.
a. Middle class ⇒ Both VAGUE and AMBIGUOUS
Middle class is non specific because it is used as a blanket term for people or things not in either first or lower class. It also has multiple meanings.
b. Odd number ⇒ NEITHER
c. Gold ⇒ AMBIGUOUS
Gold has several meanings such as being a mineral, medium of exchange or even a color.
d. Bank ⇒ AMBIGUOUS
Bank also has different meanings. It could be a financial institution, land next to water or even a repository for blood.
e. Opportunity ⇒ VAGUE
Opportunity is vague unless the opportunity is described.
f. Jaguar ⇒ AMBIGUOUS
Jaguar has multiple means. It could be a animal or it could be a car.
g. Credit ⇒ AMBIGUOUS
Credit has several meaning as well. It could refer to loans, financial entry, increase in bank account etc.