This reaction is a double replacement reaction. Hydrogen in the hydrogen fluoride gets replaced by sodium of the sodium hydroxide. HF is a weak acid and NaOH is a strong base. So, double replacement produces sodium fluoride and water molecules.
They would all strike the ground at the same time. If air resistance is neglected for example in an airless tube, then gravity is the only force acting on them and it has the same effect on them dropping so the drop at the same speed.
Answer:
1331.84 m/s
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity = 0
s = Displacement = 490 km
a = Acceleration
g = Acceleration due to gravity = 1.81 m/s² = a
From equation of linear motion

The speed of the material must be 1331.84 m/s in order to reach the height of 490 km