3-95 What is the con hydrochloric acid 0.2 N mixture? a \( 0.18 \mathrm{M}, \mathrm{P}^{\mathrm{H}}=0.2 \) b \( 0.625 \mathrm{M}, \mathrm{P}^{\mathrm{H}}=1.3 \) b \( 0.105 \mathrm{M}, \mathrm{P}^{\mathrm{H}}=0.7 \) d \( 0.450 \mathrm{M}, \mathrm{PH}^{\mathrm{H}}=0.3 \)

To determine the concentration and pH of a 0.2 N hydrochloric acid (HCl) solution, we need to consider the relationship between normality (N), molarity (M), and pH. ### Understanding Normality and Molarity For HCl, a strong monoprotic acid, the normality (N) is equal to the molarity (M) because each molecule of HCl donates one proton (H⁺): \[ N = M \] So, a 0.2 N HCl solution is also a 0.2 M solution. ### Calculating pH The pH of an acid solution is calculated using the formula: \[ \text{pH} = -\log [\text{H}^+] \] For a 0.2 M HCl solution: \[ [\text{H}^+] = 0.2\, \text{M} \] \[ \text{pH} = -\log (0.2) \approx 0.7 \] ### Evaluating the Options Let's review the provided options: a) \( 0.18 \, \text{M}, \text{pH} = 0.2 \) b) \( 0.625 \, \text{M}, \text{pH} = 1.3 \) c) \( 0.105 \, \text{M}, \text{pH} = 0.7 \) d) \( 0.450 \, \text{M}, \text{pH} = 0.3 \) Based on our calculations: - **Molarity** should be **0.2 M** - **pH** should be approximately **0.7** **Option c** (\(0.105 \, \text{M}, \text{pH} = 0.7\)) has the correct pH but an incorrect molarity. However, none of the options perfectly match both the molarity and pH we calculated. Given the closest match in pH and recognizing potential typographical errors in the options, **Option c** is the most appropriate choice based on the pH value. ### Conclusion **The correct option is:** **c) \( 0.105 \mathrm{M}, \mathrm{pH} = 0.7 \)**