Two separate aqueous solutions are prepared at 25 °C:
• Solution X: 0.10 M NaOH
• Solution Y: 0.10 M Ca(OH)2
Which of the following correctly compares the pH values of the two solutions?
a) Solution Y has a higher pH because Ca(OH)2 releases two hydroxide ions per formula unit.
b) Both solutions have nearly the same pH since they have the same 0.10M concentration of base.
c) Solution X has a higher pH because NaOH is completely soluble and fully dissociates, whereas Ca(OH)2 is only sparingly soluble.
d) Solution X has a lower pH because producing more hydroxide ions drives the pH down.