Which is generally stronger? a queen or two rooks?

The Queen is 9 points and two rooks are 10 : so that way two rooks are stronger than a queen .. But everything depends on the position . The Queen needs some help so at the start of the game when there are other pieces on the board a queen may be stronger than two rooks .. In the end game it would depend on the pawn structure . If all pawns are gone and it is only tne Q vs the 2 rooks in the end game then the rooks can protect each other and attack and defend equally well . So my conclusion : depends on the position but in general 2 rooks more powerful in the end game and the Queen if we were to start the game at move 0 with all pieces in place but one side with Queen and the other with two Rooks ...

I mostly think a queen is better than 2 rooks cause it can give double attacks and checks and is more dangerous

It depends on the situation. The points system is is just a guide, but pieces can change in value depending on whether the board is mostly open or is conjested. (For example, a bishop is more useful in an open board whereas a knight is more useful in a congested board). In general though, I think two rooks are better because you can command two ranks/files instead of one, and can command more of the board with them.

Whether Queen or Rook(s) is stronger often depends on general positions of the king and pawn formation in close proximity to the monarch. 

If the hostile King is airy and open the Queen usually get the upper hand. 

The rooks require coordination to work together. 

The Queen is able to give some cunning/menace checks in case threatened.

Generally (generally), two rooks are stronger. 

SmyslovFan «A natural assumption is that the two rooks will be stronger than the queen in the majority of positions; another is that a material balance is struck when the side with the queen has an extra pawn. I must admit that, when I examined top-flight games from my database, I was surprised to see that the queen outscored the rooks. I would have predicted a small edge for the rooks but in fact the side with the queen managed 55%»

CONNECTED ON THERE OWN THEY ROOKS ARE BETTER

I just ran a database check of Q vs 2 Rs, no minor pieces and the pawn structure being symmetrical. In other words, pure examples, "all other things being equal". 

The side with the two rooks scores 62%-38%. 

Here's one example from the hundreds of games that came up:

I agree, if there are a bunch of minor pieces on the board, the Q may prove to be stronger in a practical setting. It's very difficult to coordinate the minor pieces, as Fischer showed against Portisch. But in pure examples such as the one above, the Rooks are generally better. 

It would be nice if you cited your sources.

2 rooks can checkmate without king help, queen cant

Well, K+R vs. K mate is also easier than K+B+B vs. K, and still I would be happy to trade one of my rooks for two bishops in virtually any stage of the game.

Take a look at the position in post 131. There is nothing special about that position, and yet it was clear that White was striving for a draw while Black was working for the victory. 

In general, when all things are equal and there are no minor pieces on the board, the Rooks are better than the Q.

Qs work really well with minor pieces, especially Knights.  

it depends on the position at hand.  Open position with the center open, Q is usually a bit better, locked pawn structure with few weaknesses and 1 open file, and the rooks will have a small edge.

It's really based on the player. For me, I would say a single Queen is better since it's a single piece that has so much flexibility on the board. Plus, you only have to keep one piece alive instead of two, and two Rooks would require two moves to move both of them. I guess it also depends on your opponent and their current standing, since certain pieces would be better in certain situations.

Penalty for the rook pair (Larry Kaufman called it "principle of redundancy" Although how much of penalty implied is unknown. In theory rook pair, knights and queens suffers from this. 

Here is what Korchnoi said about having two queens.

"The game was drawn, with Korchnoi an extra queen. Later he explained something extremely strange... 'The board is too small for two queens!'>

his full statement.. 

"During the analysis, I discovered something very remarkable: the board is simply too small for two Queens of the same color. They only get in each other's way. I realize that this might sound stupid, but I fully mean it. The advantage is much less than one would expect by counting material."

taken from Mastering Tactical Ideas by Minev."

Yup, having two Qs may be clearly worse than having a Q and 2 Rs. That would definitely be a special case. 

Bronstein once pointed out that if you have a Q and R and the initiative against an exposed K, you can usually force mate. That may sound dead obvious, but that means that your opponent could have two Qs and still be lost. 

Major pieces are really, really powerful. 

The way to judge the relative merit of Rooks vs Qs is when there are no other pieces to mess with the calculus. That's why I focused on positions where there are no other pieces, and only pawns to consider. (Pawns aren't pieces, their piece wannabes. That's why they aren't given a "P" in algebraic notation!)

 HI: HERE is an interesting answer to your question. IF two strong players  are in that situation it will usually be drawish. YES friends i said drawish. EVEN the great one bobby fischer asked for a draw in that very situation  many years ago when he played in a tourney in philadelphia. I don,t know  if  it was world open or not. THE guy he played was tony kapany and fischer who was known to never play for a draw actually asked tony for a draw in that game!  look it up it is a very good game. IT is a good example of that q against 2 rooks.

I am not expert in those kind of endgames, but I would personally feel more comfortable having the queen.