Chemistry Question from JEE Main 2025 · 29 January, Shift 2

Drug X becomes ineffective after $50\%$ decomposition. The original concentration of drug in a bottle was $16 \, \text{mg/mL}$ which becomes $4 \, \text{mg/mL}$ in $12$ months. The expiry time of the drug in months is _____ . Assume that the decomposition of the drug follows first order kinetics.