I saw a Cambridge grammar article discussing whether to use 'colour pencils' or 'coloured pencils'. This piqued my interest quite a bit. However, the article only talked about how camparatively popular these terms are, it never said which one is grammatically correct. So below are two examples I thought of:
What colour/coloured car is your favorite?
Which colour/coloured apple would you like, red or green?
In both examples, I am tempted to use 'coloured', since it would be a participle turned adjective. What's interesting is that 'colour' actually seemed to be the more popular of the two whether it's proper usage or not. So which one should I use in either example sentences? Could it be that native speakers prefer using 'colour' because it rolls off the tongue easier?
Thanks a bunch in advance.