άσπρος is masculine, άσπρη is feminine, άσπρο is neuter in the nominative case.

In the accusative, it's άσπρο - άσπρη - άσπρο.

No :) It's a coincidence.

The spir- bit of aspirin is from the scientific name of a plant and is ultimately related to "spiral", and the a- is short for "acetylated".

"Μία λευκή πάπια" is an accepted alternative already. ^.^

I do not hear any κ in άσπρη. I checked both slow speed and regular speed audio in the incubator, they both sound fine. However, do keep in mind that this is not a native speaker talking, but a TTS (Text-To-Speech) program. So, it's relatively normal for some sentences to sound slightly unnatural. ^.^