An example of a general formula of an acid is
<span>HCl
This is called as hydrochloric acid or hydrogen chloride.
H represents for the atom of Hydrogen
and Cl represents for the atom of Chlorine
Since their charges are -1, and +1, it's ratio is 1:1</span>
Thus problem is providing us with the mass of iron (III) oxide as 12.4 g so the moles are required and found to be 0.0776 mol after the calculations:
<h3>Mole-mass relationships:</h3>
In chemistry, we use mole-mass relationships in order to calculate grams from moles and vice versa. In this case, since we are given the mass of iron (III) oxide as 12.4 g one can calculate the moles by firstly quantifying its molar mass:

Then, we prepare a conversion factor in order to cancel out the grams and thus, get moles:

Learn more about mole-mass relationships: brainly.com/question/18311376
The maximum negative displacement of a wave is the same as its amplitude.
As a wave travels through space, its particles are sometimes above the
<em>x</em>-axis (+) and sometimes below it (-).
The maximum displacement from the axis is the <em>amplitude</em> of the wave.
The amplitude of the wave is the <em>same in both the positive and negative directions</em>.