Answer:
1. Hydrogen 
2. Helium
Explanation:
Nuclear fusion is when two atoms of Hydrogen join together to form one Helium atom.
 
        
             
        
        
        
The answer is the third graph
        
                    
             
        
        
        
Cosmic background radiation is electromagnetic radiation from the sky with no discernible source. The origin of this radiation depends on the region of the spectrum that is observed. 
        
                    
             
        
        
        
Answer:
W = 100000 J = 100 KJ
Explanation:
Here we will use the most basic and general formula of work, which is as follows:

where,
W = Work Done = ?
F = Force Required = 200 N
d = Length of Track = 500 m
Therefore,

<u>W = 100000 J = 100 KJ</u>
 
        
             
        
        
        
Answer:
Explanation:
Ionization Energy Trends
Ionization energy is the energy required to remove an electron from a neutral atom in its gaseous phase. Conceptually, ionization energy is the opposite of electronegativity. ... As a result, it is easier for valence shell electrons to ionize, and thus the ionization energy decreases down a group