Answer
Only puck 2 can be in equilibrium.
Work Step by Step
Because the axis of rotation passes through the center of the hockey puck, all forces passing through the center of the puck produce no torques.
An object in equilibrium has its net torque $\sum\tau$ equal zero. Puck 1, 3 and 4 all have two forces applied at the outer edge of the puck, but because they point in the same direction, they cannot produce torques in opposite direction. Therefore, the net torque cannot be zero.
We know that $\tau=Fl$. Puck 5 has 2 forces on the outer edge pointing in opposite direction, but because they have different magnitudes $2F$ and $3F$ yet similar lever arm $l$, so the torques produced cannot cancel each other out completely to result in a zero net torque.
Therefore, only puck 2 can be in equilibrium.
