The answer is Column, however if you want to know the scientific word for it, it is also known as a group
(extra fact, a row is called a period)
(6) first choice: the frequency appears higher and wavelength is shorter.
The car approaches a stationary observer and so the sound will appear to have shorter wavelength. This creates an effect of its siren to sound with higher frequency than it would do if both were stationary.
(7) The Doppler formula for frequency in the case of a stationary observer and source approaching it is as follows:

The wavelength is then

The third choice "0.80m; 431Hz" is correct
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:

Potential energy is energy that is found in a system, grounded on the position of objects. The Coulomb (C) is the unit of charge, and the unit of electric potential is the Volt (V), which is equivalent to (J/C) or Joule per Coulomb.So the formula for this is potential = kQ / d, plugging in the given from the questions will give us:potential = 8.99e9N·m²/C² * 1.602e-19C / 0.053e-9m = 27 V
Well velocity is a vector quanity and we can brake vectors in to verticle and horizantal componontes threw these two formulas Vcostheta=Vx and Vsintheta=Vy