Answer:
1. pH = 1.23.
2. 
Explanation:
Hello!
1. In this case, for the ionization of H2C2O4, we can write:

It means, that if it is forming a buffer solution with its conjugate base in the form of KHC2O4, we can compute the pH based on the Henderson-Hasselbach equation:
![pH=pKa+log(\frac{[base]}{[acid]} )](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%28%5Cfrac%7B%5Bbase%5D%7D%7B%5Bacid%5D%7D%20%29)
Whereas the pKa is:

The concentration of the base is 0.347 M and the concentration of the acid is 0.347 M as well, as seen on the statement; thus, the pH is:

2. Now, since the addition of KOH directly consumes 0.070 moles of acid, we can compute the remaining moles as follows:

It means that the acid remains in excess yet more base is yielded due to the effect of the OH ions provided by the KOH; therefore, the undergone chemical reaction is:

Which is also shown in net ionic notation.
Best regards!
Answer:
5.995 psi
Explanation:
30 psi = 2.04 atm
75 mL = 0.075 L
15 mL = 0.015 L
0.075 L/ 2.04 atm = 0.015 L/x
0.075x = 0.0306
x = 0.408
0.408 atm = 5.995 psi
Mixture; it contains water, surgar, fat, protein, etc.
Heya!
HERE IS YOUR ANSWER:
Electrons = 50
Atomic number = 50
so, the Element is stannum (Sn)