First of all, this probably isn't the right forum for these sort of questions. There are a lot of forums out there specifically designed to help people with programming homework.
For the first one try running all three of those lines through a compiler. If I understand Java then only one should be legal. (Define k first)
For the second one, search Wikipedia for all those terms. I looked for the one I thought it was and there was no question in my mind that it was right.
For the third one, just look at the words and which one makes sense with "always true for ... class". Or go back to Wikipedia.
For the fourth one, look at Wikipedia's article on scope.
For the fifth one, what's the last line of a function that isn't void?
Sorry, that I won't come right out and tell you the answers, but I managed to figure these all out in less than five minutes, so I'm sure you can do the same now that you know where to look. Plus, it's best to do your own homework.
I'd recommend finding a programming forum if you're going to need help debugging code. You'll probably get a better/faster response with that.