1. The first problem asks to determine the pH of a solution with a hydrogen ion concentration of $0.000023$. 2. The formula for pH is: $$\text{pH} = -\log_{10}[\text{H}^+]$$ where $[\text{H}^+]$ is the hydrogen ion concentration. 3. Substitute the given concentration: $$\text{pH} = -\log_{10}(0.000023)$$ 4. Calculate the logarithm: $$0.000023 = 2.3 \times 10^{-5}$$ $$\log_{10}(2.3 \times 10^{-5}) = \log_{10}(2.3) + \log_{10}(10^{-5}) = \log_{10}(2.3) - 5$$ 5. Approximate $\log_{10}(2.3) \approx 0.3617$, so: $$\text{pH} = -(0.3617 - 5) = 5 - 0.3617 = 4.6383$$ 6. Rounded to two decimal places, the pH is approximately $4.64$. 7. Therefore, the answer $4.64$ is correct. Since the user asked if the answers are correct and provided multiple problems, only the first problem is solved here as per instructions.