They are the element symbols. Too many to list here, look up a periodic table.
X-rays have high energy and can penetrate matter that light cannot.
Answer:

Explanation:
It is given that,
A planar electromagnetic wave is propagating in the +x direction.The electric field at a certain point is, E = 0.082 V/m
We need to find the magnetic vector of the wave at the point P at that instant.
The relation between electric field and magnetic field is given by :

c is speed of light
B is magnetic field

So, the magnetic vector at point P at that instant is
.
Explanation:
Average speed = change in distance / change in time
In other words, the average speed is the slope of the line connecting two points on the graph.
It would be hotter near the Earth's equator and colder near Earth's poles.