ANS:A - 10^-11

To determine the hydroxyl ion (OH-) concentration in a solution given its pH value, you can use the relationship between pH and the concentration of hydrogen ions (H+), which is given by the equation: pH=−log⁡[𝐻+]pH=−log[H+] In a neutral solution, where pH is 7, the concentration of hydrogen ions is 10−710−7 moles per liter (M). As pH decreases, indicating increasing acidity, the concentration of hydrogen ions increases. Conversely, as pH increases, indicating increasing basicity, the concentration of hydrogen ions decreases. Given that pH 3 is acidic, we know that the concentration of hydrogen ions ([𝐻+][H+]) is greater than 10−710−7 M. The hydroxyl ion concentration ([𝑂𝐻−][OH−]) in water can be calculated using the relationship: 𝐾𝑤=[𝐻+][𝑂𝐻−]Kw​=[H+][OH−] Where 𝐾𝑤Kw​ is the ion product of water, which is 10−1410−14 at 25°C. So, if we know the concentration of hydrogen ions, we can find the concentration of hydroxyl ions using this relationship. Let's calculate the concentration of hydrogen ions: pH=−log⁡[𝐻+]pH=−log[H+] 3=−log⁡[𝐻+]3=−log[H+] Solving for [𝐻+][H+]: [𝐻+]=10−3 M[H+]=10−3M Now, we can use this concentration to find the concentration of hydroxyl ions: 𝐾𝑤=[𝐻+][𝑂𝐻−]Kw​=[H+][OH−] 10−14=(10−3)([𝑂𝐻−])10−14=(10−3)([OH−]) Solving for [𝑂𝐻−][OH−]: [𝑂𝐻−]=10−1410−3=10−11 M[OH−]=10−310−14​=10−11M So, the hydroxyl ion concentration in a solution with pH 3 is 10−1110−11 M. Therefore, the correct option is 10−1110−11.