To fill up all of the valence electrons we must have 8 electrons total to have an ionic bond. In this case Lithium is in group 1 and so only has 1 valence electron and so it can bond with elements from group 17, since 7 + 1 = 8. However, this unknown element did bond with beryllium, and beryllium is in group 2 so it must bond with an atom that has 6 valence electrons. The elements that have 6 valence electrons are in group 16 not group 2. So the result does not support her conclusion.
A if it is one answer and if it’s multiple choice A and D
Answer:
150 m/s
Explanation:hope that helps
Answer:

Explanation:
From the question we are told that:
Wavelength
m
Refraction Index 
Generally the equation for Destructive interference for Normal incidence is mathematically given by

Since Minimum Thickness occurs at
At 
Therefore


