Is tuba a proper noun

Answer 1

No, the noun 'tuba' is a commonnoun, a general word for a type of musical instrument.

A proper noun is the name of a specific person, place, or thing. A proper noun for the common noun 'tuba' is the name of a specific tuba, for example:

• Miraphone 1281 Petruschka Series 5-Valve 5/4 F Tuba
• Jupiter 384 Series Convertible 3-Valve 4/4 BBb Tuba

Or even:

• Tuba Street, Los Angeles, CA