I believe it is C, but correct me if I'm wrong.
Answer:
When two atoms have shared electrons, it is not distinguishable from what atom they are because they are shared in the same orbit, it is called a covalent bond.
Step-by-step explanation:
Atoms in a covalent bond share one or more electrons in the last of their orbitals, the number of electrons in the last orbital will depend on the element in question.
Answer:
The steps have been shown in the solution below
Step-by-step explanation:


LHS=RHS Hence, proved.
<span>The measure of dispersion that indicates how much scores in a sample vary around the mean of the sample is the standard deviation.</span>
Answer:
156
Step-by-step explanation:
Let the sum of the set of numbers = S
So....the mean would be calculated as the sum of the set divided by its number of entries, or :
S / 12 = 13 ....... multiply both sides by 12
S = 13 * 12 = 156 .....so.....the sum is 156