Which descending order follows the usual relative basic strengths of the conjugate-base ions nitrate (NO₃⁻), chloride (Cl⁻), bromide (Br⁻) and iodide (I⁻)?

Explanation

The conjugate base of a stronger acid is weaker. Relative acid strength decreases through HI, HBr, HCl and HNO₃, so descending conjugate-base strength is nitrate, chloride, bromide, iodide. All four anions have negligible basicity in water; the ordering expresses relative strengths beyond water’s levelling effect.