2. if the incline is frictionless, then the acceleration of the mass down the incline is $a = g\sin{\theta}$ , where ${\theta}$ is the angle of the incline w/r to the horizontal.
you were given a displacement (5 m), an initial velocity (0), and a final velocity (7 m/s) ... use your knowledge of kinematics to determine the actual acceleration of the mass, then compare it with the value of $g\sin(30)$.