This study assessed item parameters of the Chemistry mock examinations administered to senior secondary school students in Akwa Ibom State using the classical test theory framework. Specifically, the study examined item difficulty, item discrimination, distractor functioning and the reliability. The population comprised all senior secondary two and three Chemistry students in public secondary schools across the three senatorial districts of Akwa Ibom State. A sample of 2,000 students was drawn through a multistage sampling procedure. Data were collected from students’ responses to a 50-item multiple-choice Chemistry mock examination administered during the 2024/2025 academic session. Item analysis was conducted using descriptive statistics such as item difficulty indices, discrimination indices, distractor analysis, and Kuder-Richardson 20 (KR-20) for internal consistency. Results revealed that 64% of the items were of moderate difficulty, 20% were very difficult and 16% were too easy. The mean discrimination index was 0.32, indicating that most items could differentiate between high- and low-achieving students. However, 10 items showed poor discrimination and required revision. The reliability coefficient (KR-20) of 0.81 indicated good internal consistency. The study recommends periodic item analysis to improve Chemistry examination quality and enhance decision-making in schools
Keywords: Reliability, item difficulty, item discrimination, item parameters, option distraction
