<h2>Answer:</h2>
What does Atomic number represents ___________.
What does the Mass number represent ___________
Periods are _____________ rows.
Groups are _____________ columns.
Total elements in periodic table are _____________.
He proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another.
The quality or state of being volcanic.
<span><u><em>Answer:</em></u>
All of the above
<u><em>Explanation:</em></u>
Vertebrates are a class of creatures falling under kingdom "<u>Animalia</u>" that are characterized by the presence of an internal skeleton composed of bones.
<u>Vertebrates are characterized by the following:</u>
1- presence of internal skeleton
2- developed brain
3- the presence of an advanced nervous system connected to the brain
4- presence of muscles that allow movement
5- protective skin
6- circulation of blood in the bodies in the vessels
Comparing the mentioned characteristics with the options given, we will find that the most suitable answer is: <u>"all of the above"</u>.
Hope this helps :)</span>
