<u>Answer:</u> The law that related the ideal gas law is 
<u>Explanation:</u>
There are 4 laws of gases:
- <u>Boyle's Law:</u> This law states that pressure is inversely proportional to the volume of the gas at constant temperature.
Mathematically,

- <u>Charles' Law:</u> This law states that volume of the gas is directly proportional to the temperature of the gas at constant pressure.
Mathematically,

- <u>Gay-Lussac Law:</u> This law states that pressure of the gas is directly proportional to the temperature of the gas at constant pressure.
Mathematically,

- <u>Avogadro's Law:</u> This law states that volume is directly proportional to number of moles at constant temperature and pressure.
Mathematically,

Hence, the law that related the ideal gas law is 
Answer:
The pH of the buffer solution = 8.05
Explanation:
Using the Henderson - Hasselbalch equation;
pH = pKa₂ + log ( [HPO₄²-]/[H₂PO4⁻]
where pKa₂ = -log (Ka₂) = -log ( 6.1 * 10⁻⁸) = 7.21
Concentration of OH⁻ added = 0.069 M (i.e. 0.069 mol/L)
[H₂PO4⁻] after addition of OH⁻ = 0.165 - 0.069 = 0.096 M
[HPO₄²-] after addition of OH⁻ = 0.594 + 0.069 = 0.663 M
Therefore,
pH = 7.21 + log (0.663 / 0.096)
pH = 7.21 + 0.84
pH = 8.05