Supplementary angles add up to 180°.
If one is 40°, then the other is (180° - 40°) = 140° .
None of those choices describes a plane.
Choice 'C' is the only example of a plane.
Answer:
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Answer:

Explanation:
The original equation is:

We notice that:
- we have 1 atom of Fe on the left, and 2 atoms of Fe on the right
- we have 2 atoms of O on the left, and 3 atoms of O on the right
Therefore, the equation is not balanced.
In order to balance it, we can add:
- a coefficient 3 in front of 
- a coefficient 2 in front of 
So we have:

Now the oxygen is balanced, but the iron it not balanced yet, since we have 1 Fe on the left and 4 on the right. Therefore, we should add a coefficient 4 on the Fe on the left:

They are too small are never in the same place. Electrons are constantly moving in random motion within the electron cloud, making them impossible to follow.