ANS:C - 7

If a solution contains equal concentrations of hydroxide (𝑂𝐻−OH−) and hydrogen (𝐻+H+) ions, it implies that the solution is neutral, as the concentration of 𝐻+H+ ions is equal to the concentration of 𝑂𝐻−OH− ions. In neutral water, the concentration of 𝐻+H+ ions is 10−710−7 moles per liter (written as [𝐻+]=10−7[H+]=10−7), and the concentration of 𝑂𝐻−OH− ions is also 10−710−7 moles per liter (written as [𝑂𝐻−]=10−7[OH−]=10−7). The pH of a solution is defined as the negative logarithm of the concentration of 𝐻+H+ ions: pH=−log⁡[𝐻+]pH=−log[H+] In a neutral solution where [𝐻+]=[𝑂𝐻−]=10−7[H+]=[OH−]=10−7, the pH is: pH=−log⁡(10−7)=−(−7)=7pH=−log(10−7)=−(−7)=7 Therefore, the pH value of a solution containing equal concentrations of hydroxide and hydrogen ions will be 77​.