Which statements regarding the Henderson-Hasselbalch equation are true?

– The equation relates the pH of a solution to the pKa and the ratio of the concentrations of the conjugate base and the weak acid. – It is derived from the expression of the acid dissociation constant (Ka). – It assumes ideal behavior, which is generally valid for dilute solutions. – It is applicable to buffer solutions containing weak acids and their conjugate bases or weak bases and their conjugate acids.