Answer:
D would be the best answer
Explanation:
A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.
Answer:
Average atomic mass = 58.51047 amu
The symbol is 
Explanation:
The formula for the calculation of the average atomic mass is:
Given that:
For first isotope:
% = 68.274 %
Mass = 57.9353 amu
For second isotope:
% = 26.095 %
Mass = 58.9332 amu
For third isotope:
% = 1.134 %
Mass = 61.9283 amu
For fourth isotope:
% = 3.593 %
Mass = 63.9280 amu
For fifth isotope:
% = 0.904 %
Mass = 63.9280 amu
Thus,

Average atomic mass = 58.51047 amu
The symbol is 