The answer is, All of the above
The best and most correct answer among the choices provided by the question is the second choice , b. sodium hydroxide .
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To find the concentration of hydronium ions, take 10 raised to the negative pH:
10^-9.56= 2.75 x10^-10M
To find the concentration of hydroxide ions, take 10 raised to the negative pOH: 10^-4.44 = 3.63 x10^-5M