no. only on number cards
No, you cannot put a wild card on a Draw 4 card in Uno.
Yes, in Uno, you can end the game by playing a Wild Card if it is your last card and you declare "Uno" before playing it.
No, you cannot end a game of Uno by playing a Skip card.
No, you cannot end a game of Uno by playing a wild card.
No, you cannot end a game of Uno with a Draw 4 card.
No, you cannot end the game of Uno by playing a skip card.
No, you cannot put a black card on top of another black card in Uno.
No, you cannot put a Skip card on top of a Draw 2 card in Uno.
No, you cannot put a Skip card on top of a Draw 4 card in Uno.
No, you cannot put a skip card on top of another skip card in Uno.
In Uno, you cannot put a Wild Card on top of another Wild Card.
Yes, in the game of Uno, you can say "Uno" before you put down your second-to-last card.