There are NO true statements on the list you provided.
<span>node spacing = half of wavelength = 3 cm
velocity = 10 cm/s = freq * wavelength
hench freq = 10/6 = 5/3 = 1.7 hz</span>
Using the kinematic equation d = V_0 * t + 1/2 * a * t^2, where d is height you can rewrite this to be d = 1/2*g*t^2 or 4.9t^2
g = a because this is a free fall
d = 1/2 * 9.81m/s^2 * 2.5^2
d = 30.65625m
d = 30.7m