Hey there!
Option A
A climate crisis is occurring in California where sudden forest fires occur due to this .
Answer:
a transverse (sort of a plot of a sine or cosine graph, basically)
b longitudinal
c Electromagnetic (an electric wave and a magnetic wave travelling together at right angles to each other)
Explanation:
Answer:
The elastic potential energy of the spring change during this process is 21.6 J.
Explanation:
Given that,
Spring constant of the spring, 
It extends 6 cm away from its equilibrium position.
We need to find the elastic potential energy of the spring change during this process. The elastic potential energy of the spring is given by the formula as follows :

So, the elastic potential energy of the spring change during this process is 21.6 J.
Answer: 
Explanation:
The mean free path
of an atom is given by the following formula:
(1)
Where:

is the Universal gas constant
is the absolute standard temperature
is the diameter of the helium atom
is the Avogadro's number
absolute standard pressure
Knowing this, let's find
from (1), in order to find the radius
of the helium atom:
(2)
(3)
(4)
If the radius is half the diameter:
(5)
Then:
(6)
(7)
However, we were asked to find this radius in nanometers. Knowing
:
(8)
Finally:
This is the radius of the helium atom in nanometers.