The larger the Ka, the smaller the pKa and the __________ the acid.

The larger the Ka, the smaller the pKa and the __________ the acid.

• A. Weaker
• B. Less acidic
• C. Stronger
• D. More basic

Answer: (C)

The key idea is the link between acid strength, Ka, and pKa. A larger Ka means the equilibrium lies more toward dissociation, so more H+ ions are released in solution. Since pKa is defined as the negative logarithm of Ka, increasing Ka makes pKa smaller. That combination means the acid is stronger. So the blank is filled by “stronger.” To see why the other ideas don’t fit: a stronger acid is not weaker or less acidic; those would correspond to smaller Ka and larger pKa. And stronger acids are not more basic—they are less basic as they donate protons more readily.

The key idea is the link between acid strength, Ka, and pKa. A larger Ka means the equilibrium lies more toward dissociation, so more H+ ions are released in solution. Since pKa is defined as the negative logarithm of Ka, increasing Ka makes pKa smaller. That combination means the acid is stronger. So the blank is filled by “stronger.”

To see why the other ideas don’t fit: a stronger acid is not weaker or less acidic; those would correspond to smaller Ka and larger pKa. And stronger acids are not more basic—they are less basic as they donate protons more readily.