I have not read the article, and so I don't know in what context this is referring to. But I do know that <span>Infra-sound is made up of a really low frequency sound, beyond the range of hearing by humans. </span>Helpful? :)
Answer:
is it some kind of code??...........
Atoms<span> are </span>arranged in molecular compounds in groups.
<span>
For </span>covalent compounds<span>: </span>
<span>consider drawing the lewis structure of the covalent compound in question, putting the atom which is least electronegative (save hydrogen) in the center.
</span>
Density = mass/volume
Density = 81g/0.9cm³
Density = 90g/cm³
: )
