This would be more of a chemistry question. Remember magnesium has a charge of 2+, and would need to hand off its two extra electrons. Fluorine can only take one electron at a time, so there needs to be two fluorines to take one magnesium's 2 electrons.
With lithium, it has a +1 charge, so it has one extra electron, which it can hand off to just 1 fluorine atom.
Another way of looking at this is:

+ 2

= MgF2 (the charges must balance out to zero)

+

= LiF (the charges balance out to zero)
Explanation:
It varies with altitude, but at sea level, it's 9.8 m/s².
Answer:
3.57 MJ
Explanation:
ASSUMING it's fresh water with density of 1000 kg/m³
W = ΔPE = mgΔh = 14.0(1000)(9.81)(26.0) = 3,570,840 J
Salt water would require more.
Answer:
Acceleration
Explanation:
The quantity of the rate of change of velocity is termed the acceleration of the body.
Acceleration is the rate of change of velocity with time;
A =
A is the acceleration
v is the final velocity
u is the initial velocity
t is the time taken