"A black tea" is also a correct answer
Only if you refer to a cup of tea (or, perhaps, some packaged item). Otherwise tea is uncountable.
Or if you're talking about different kinds of tea. "This is a black tea with hints of vanilla."
Pretty lousy pronunciation of чай.
Aren't there also times when it is spelled чая ?
"Чая" is the genitive case of "чай".
So i type in "black" in duo's translator, get чёрной, which apparently is wrong.
I use another translator and get черный
What the h#ll, which is right?
The endings of adjectives match the nouns you attach them to (e.g., чай is masculine).
In china they call it красный чай