Answer:
Because of the less reactivity of copper.
Explanation:
As well as being resistant to the elements and thereby less likely to be affected by rainfall, hail, and mildew than other types of roofing, copper is also one of the most fireproof materials available. Copper is also highly resistant to thermal changes and thereby doesn't deteriorate quickly.
Magnesium would also corrode PDQ. Magnesium sheeting would also pose an unacceptably high fire hazard.
Answer:
2.16 MeV
Explanation:
To determine the amount of work done that is needed to assemble the atomic mass; we need to apply the equation;
U = 
where:
= proportionality constant = 
e = magnitude of the charge of each electron = 
r = length of each side of the vertex = 
So; replacing our values into above equation; we have:
U = 
U = 3.456 × 10 ⁻¹³ J
If we have to convert our unit from J to Mev; then we are going to have:
U = 3.456 × 10 ⁻¹³ J 
U = 2.16 MeV
Therefore, the amount of work done needed to assemble an atomic nucleus = 2.16 MeV
The process is called, Fixation