Answer:
a) 
b) 
c) 
d) 
Explanation:
a) We can find the electron's speed by knowing the kinetic energy:

Where:
K: is the kinetic energy = 1.59 keV
m: is the electron's mass = 9.11x10⁻³¹ kg
v: is the speed =?

b) The electron's speed can be found by using Lorentz's equation:
(1)
Where:
F: is the magnetic force
q: is the electron's charge = 1.6x10⁻¹⁹ C
θ: is the angle between the speed of the electron and the magnetic field = 90°
The magnetic force is also equal to:
(2)
By equating equation (2) with (1) and by solving for B, we have:

c) The circling frequency is:

Where:
T: is the period = 2π/ω
ω: is the angular speed = v/r

d) The period of the motion is:

I hope it helps you!
I believe the answer is the white dwarf.
The sun will cool then heat up again is my understanding. Hope this helps
Answer: The chemical energy of reactants is greater than the chemical energy of products.
Explanation: In the given reaction

It can be seen that the energy has been released. Thus we can say that reactants have converted to products by release of energy. Thus energy of products is less as compared to energy of reactants as some of the energy has been released.
Answer:
The Graph Shows World Disasters.
Answer Pt.2:
As we all can see the tornado's Have the highest ratings of natural disasters, Hurricane's happen the next most, Landslide's happen less often, Wildfires also happen less often whereas Earthquakes nearly never happen, they are very rare to the world.
You'd use the equation kinetic energy=mass*0.5*speed^2
So you'd rearrange this to get mass =kinetic energy /0.5 *speed^2
Which is mass= 1500J/0.5*35^2
=2.44897959183673469........kg