"What colour is the flag of Wales?"

Translation: Beth ydy lliw baner Cymru?

[ChrisMSully]

I would say pa liw ydy'r baner cymru, though I suppose I should use the exact wording of the question ...

[SirFurboy]

I think they did it that way because "baner" is feminine, and they don't want to confuse you with the mutation.

[iamOwenG]

I think you did use the exact wording... pa/which liw/colour ydy'r/is the baner/flag cymru/of wales

[mizinamo]

Do you need the 'r there?

I would have thought that baner Cymru would be definite by default, since Cymru (a proper noun) is definite.

[EllisVaughan]

That would make sense but it is an incorrect translation of the sentence given.