The question is incomplete, here is the complete question:
What volume (mL) of the partially neutralized stomach acid having concentration 2M was neutralized by 0.01 M NaOH during the titration? (portion of 25.00 mL NaOH sample was used; this was the HCl remaining after the antacid tablet did it's job)
<u>Answer:</u> The volume of HCl neutralized is 0.125 mL
<u>Explanation:</u>
To calculate the concentration of acid, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is HCl (Stomach acid)
are the n-factor, molarity and volume of base which is NaOH.
We are given:

Putting values in above equation, we get:

Hence, the volume of HCl neutralized is 0.125 mL
Answer:
C 16
Explanation:
Since there are 6 valence electrons, this belongs in the same column as Oxygen. In fact, this is a diagram of a neutral oxygen atom with 8 total electrons.
Answer : The concentration of a solution with an absorbance of 0.420 is, 0.162 M
Explanation :
Using Beer-Lambert's law :

As per question, at constant path-length there is a direct relation between absorbance and concentration.

where,
A = absorbance of solution
C = concentration of solution
l = path length
= initial absorbance = 0.350
= final absorbance = 0.420
= initial concentration = 0.135 M
= final concentration = ?
Now put all the given value in the above relation, we get:


Thus, the concentration of a solution with an absorbance of 0.420 is, 0.162 M
Because the elements have not yet then been discovered.
Hope this helps.