KHYBER PAKHTUNKHWA PUBLIC SERVICE COMMISSION
WRITTEN EXAMINATION FOR THE POSTS OF PMS OFFICER / AETO BPS-17
(2025)
CHEMISTRY (PAPER-II)
Time Allowed: 03 Hours Total Marks: 100
Note:- Attempt any five questions. All questions carry equal marks.
Q.No.1 Discuss Molecular Orbital Theory (MOT), explaining the concepts of bonding, non-bonding, and anti-bonding molecular orbitals. Use MOT to compare the bond order, stability, and magnetic behavior of O₂⁺, N₂ and F₂. (20)
Q.No.2 Define rate law, and derive the integrated rate equations for second-order reactions with same and different concentrations of reactants with suitable examples. (20)
Q.No.3 Differentiate between physical adsorption and chemisorption. Explain Langmuir adsorption isotherm and Freundlich isotherm. (20)
Q.No.4 Define conformational isomerism and its types. Explain conformational analysis of ethane, n-butane, cyclohexane and discuss how conformation affects their stability and reactivity. (20)
Q.No.5 Classify organic halogen compounds. Differentiate between SN1 and SN2 reactions and discuss the role of nucleophile, electrophile, leaving group, substrate and solvent polarity. (20)
Q.No.6 Compare and contrast the Cannizzaro reaction and aldol condensation in terms of reaction conditions, mechanism, and products formed. (20)
Q.No.7 Discuss the structure of benzene with reference to Kekule structure, resonance concept, and molecular orbital theory. Explain how resonance energy accounts for benzene’s unusual stability and lack of addition reactions. (20)
Q.No.8 Discuss synthetic applications of the diazonium salts in the preparation of aromatic compounds through Sandmeyer and Gattermann reactions with suitable examples. (20)