A spontaneous reaction is a term that is best describe to a type of reaction wherein it is started without even with the help of an outside force. In addition to that, this kind of reaction is commonly driven by the forces of enthalpy and entropy which are essential concepts to thermodynamics.
I believe it isa refraction. hope this helps
Answer:

Explanation:
The inital electrostatic force between the two spheres is given by:

where
is the initial force
k is the Coulomb's constant
q1 and q2 are the charges on the two spheres
r is the distance between the two spheres
The problem tells us that the two spheres are moved from a distance of r=20 cm to a distance of r'=10 cm. So we have

Therefore, the new electrostatic force will be

So the force has increased by a factor 4. By using
, we find

Answer:
50.4°
Explanation:
Snell's law states:
n₁ sin θ₁ = n₂ sin θ₂
where n is the index of refraction and θ is the angle of incidence (relative to the normal).
When θ₁ = 48°:
n sin 48° = 1.33 sin 72°
n = 1.702
When θ₁ = 37°:
1.702 sin 37° = 1.33 sin θ
θ = 50.4°
Average speed =
(total distance covered)
divided by
(total time spent covering the distance)