Final answer:
The smaller the pKa, the stronger the acid.
Step-by-step explanation:
The smaller the pKa, the stronger the acid. The pKa is a quantitative measure of acid strength. For example, acetic acid (CH3COOH, pKa=4.76) is a stronger acid than ethanol (CH3CH2OH, pKa=15.9). A smaller pKa value corresponds to a larger acid ionization constant and a stronger acid.