1.Decomposition i think
2.boiling
3.It is a solid at room temperature and pressure.
4.<span>The base donates a hydrogen ion.
5.That causes the oxidation of another element
6.</span>MnO2
7.When a substance is reduced, electrons are lost.
8.True I think
9.False
10.True
Hope these are correct
<h2>
Answer:</h2>
Average atomic mass of an element is the sum of the masses of its isotopes each multiplied by its natural abundance





Se - 78
Selenium - 78
or
78/34 Se2-
Answer: the protons n neutrons
Explanation: