I believe this means equal barometric pressures, I am not completely familiar with this so if i'm wrong i sincerely apologize.
If this helped please mark me brainliest.
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<h3><u>Answer</u>;</h3>
pH = 4.38
<h3><u>Explanation;</u></h3>
Consider that ;
[H3O+] = 10-pH mol/L
Therefore; the pH is the -log of the [hydronium ion].
pH = - log [H3O+]
Thus;
pH = - log (4.2 × 10^–5)
= 4.38
Answer : The number of moles of HCl neutralize is, 0.00824 moles.
Explanation :
The given balanced chemical reaction is:

First we have to calculate the moles of 

Molar mass of
= 144 g/mol

Now we have to calculate the moles of HCl.
From the balanced chemical reaction we conclude that,
As, 1 mole of
react with 4 moles of HCl
So, 0.00206 mole of
react with
moles of HCl
Thus, the number of moles of HCl neutralize is, 0.00824 moles.