However VS but VS although

I have studied hard for the exam. _____, I failed the exam.

I am hungry _____ I am not able to finish off a whole pizza.

Sam reads books _____ he doesn't read newspapers.

I didn't tell him anything about the accident. _____, he looked very anxious.

I don't know how to play the chess. _____, I really want to learn it.

He decided to go _____ I asked him not to.

_____ the car's old, it still runs well.

I haven't got any grapefruit juice _____ I've got some orange juice. Is it okay?

She walked home by herself _____ she knew that it was dangerous.