If a running back is outside of the pocket (yes running back) and behind the line of scrimmage can they intentionally ground the ball.

Wait, who's throwing the ball?

Yes. And they do sometimes, with a caveat. The ball must cross the line of scrimmage...

...I think...

Wait, who's throwing the ball?

Running back or wide reciever on the reverse//

It's the same as a QB, it's got to be close to target and ahead of the line of scrimmage if they're in the pocket.

Tomoyo is right I believe. If the RB or WR is outside the pocket, they simply have to get it past the line of scrimmage. Same as QB.

A runningback or wide receiver can take possession of the football within the pocket (behind the line of scrimmage and within the original stance of the tight ends, I believe) and throw the ball under the same rules as the quarterback. Intential grounding I don't believe applies, if you're referring to him spiking the ball. However, they could throw it away in an intentially failed attempt (usually an overthrow) to a receiver downfield.

If a running back is outside of the pocket (yes running back) and behind the line of scrimmage can they intentionally ground the ball.

By rule, I'm certain he can. No matter which player is attempting a forward pass, the same rules and restrictions apply.

Whether he WOULD, and whether the officials would understand what was happening and apply the right rule and interpret said rule correctly, are other matters.

But no, this hypothetical running back should not be called for intentional grounding in this case.

The same rules apply to RBs as apply to QBs in this situation, as well as WRs. The rules of the game don't really separate the positions as they are in real life. It's basically "Guys who are on the offensive line" and "Guys who aren't on the offensive line".

Of course, if you could figure a way to get a Guard the football, he could probably ground the ball by the same rules as everyone else.

Isn't the rule: "line of scrimage OR within 10 yards of an eligable receiver"? When inside the pocket, of course.

If a running back is outside of the pocket (yes running back) and behind the line of scrimmage intentionally throw an incomplete pass.

First off, the question is really asking if a Half-back can throw an intentionally throw an incomplete pass.

If the ball is not thrown near a receiver, rules listed below apply.

There are NO rules applying specifically to the Quarterback in Football. Any rules referring to passing refer to a "Passer". From time to time, a team will use a trick play where a non-Quarterback to pass the ball. The half-back pass is examples of this. The QB will give the ball to a halfback who normally just runs the ball and run past the tackle. Once there, he reveals what he wants to do and throws the ball.

From http://www.nfl.com/rulebook/intentionalgrounding
Intentional Grounding of Forward Pass

1. Intentional grounding of a forward pass is a foul: loss of down and 10 yards from previous spot if passer is in the field of play or loss of down at the spot of the foul if it occurs more than 10 yards behind the line or safety if passer is in his own end zone when ball is released.
2. Intentional grounding will be called when a passer, facing an imminent loss of yardage due to pressure from the defense, throws a forward pass without a realistic chance of completion.
3. Intentional grounding will not be called when a passer, while out of the pocket and facing an imminent loss of yardage, throws a pass that lands at or beyond the line of scrimmage, even if no offensive player(s) have a realistic chance to catch the ball (including if the ball lands out of bounds over the sideline or end line).