Federal Public Service Commission (FPSC) Competitive Examination for Recruitment to BPS-17 Posts under the Federal Government
Time Allowed: 3 Hours
MAXIMUM MARKS: 100 Marks
CHEMISTRY, PAPER-I
PART-II
Attempt FIVE questions in all, Including Questions No.1 which is COMPULSORY, All questions carry EQUAL marks.
Q.2. (a) The following reaction occurs via two steps, where the first step is rate-determining step. Step I NO₂(g) + NO₂(g) → NO(g) + NO₃(g) Step II NO₃(g) + CO(g) → NO₂(g) + CO₂(g) i. Write down the rate equation for the above reaction. ii. Which molecule acts as a catalyst in this reaction? Give a reason. iii. Which molecule is an intermediate in this reaction and justify it. (12) (b) Describe Arrhenius’s equation. (8) (20)
Q.3. (a) An explosion is usually considered adiabatic, indicating negligible heat transfer, even though its rapidly expanding gaseous products are not at the same temperature as the surroundings, and the boundary permits heat transfer. Explain the phenomenon. (10) (b) Draw a working diagram for a reversible heat engine that operates with two isothermal steps and two constant-pressure steps. How many heat reservoirs are needed to operate this engine? (10) (20)
Q.4. (a) Describe Schrodinger Wave Equation for a particle in a three-dimensional box. (10) (b) Explain photoelectric effect. (8) (c) What is a wave function? Give Born’s interpretation of wave function. (2) (20)
Q.5. (a) Describe Nernst’s equation. (10) (b) Describe the significance of pH, pKₐ, and pK♭. (6) (c) What is the relationship between conductance and Kohlrausch’s law? (4) (20)
Q.6. (a) Describe three methods of mechanical phase separation. (10) (b) Briefly discuss “The Hard-Soft Acid-Base Principle.” (10) (20)
Q.7. (a) Compare Valence Bond Theory with Molecular Orbital Theory. (10) (b) What is the oxidation state? Differentiate between the oxidation state and valency / covalency of an element with suitable examples. (06) (c) Write the molecular orbital configuration of the followings: O₂⁺, O₂, O₂⁻ and O₂²⁻. (04) (20)
Q.8. Discuss the following in detail. (5 each) i. Crystal Field Theory ii. Hess’s Law iii. Electrophoresis Technique iv. Freundlich Adsorption Isotherm
CHEMISTRY, PAPER-II
Attempt FIVE questions in all, Including Questions No.1 which is COMPULSORY, All questions carry EQUAL marks.
PART-II
Q.2. (a) Arrange the following compounds in decreasing order of their relative stability. How will you proceed to determine the order practically? i. 1-hexene ii. cis-3-hexene iii. trans-3-hexene iv. 2-methyl-2-pentene v. 2,3-dimethyl-2-butene (5) (b) Explain why? (i) Poly substitution is a complicating factor in aromatic alkylation but not in aromatic nitration or halogenation. (ii) A undergoes nitration predominantly at the ortho/ para positions but B mainly at meta position. [Structure A: CH₂CH₂CN attached to Benzene ring] [Structure B: CH=CHCN attached to Benzene ring] (5) (c) Compare the basicity of the following pairs: (i) (CH₃)₃N & (CCl₃)₃N (ii) C₆H₅CH₂NH₂ & CH₃C₆H₄NH₂ (iii) 4-Nitroaniline (NC-C₆H₄-NH₂ derivative configuration) & 4-Aminobenzonitrile / Aniline derivative (iv) N-Ethylaniline (C₆H₅NHCH₂CH₃) & Acetanilide (C₆H₅NHCOCH₃) (v) Aniline & Cyclohexylamine (5) (d) Explain why? (2.5 each) (i) Tertiary carbocation is more stable than primary. (ii) Ethanol has higher boiling point than diethyl ether. (5) (20)
Q. 3. (a) Write the structural formula for more stable conformation of each of the following compounds: a) trans-1-Fluoro-3-methylcyclohexane, b) cis-1-Iodo-4-methylcyclohexane c) cis-1-tert-Butyl-4-methylcyclohexane, d) cis-1,3,5-Trimethylcyclohexane (8) (b) Mention R & S configuration of the following compounds. [Fischer projection 1: H, OH, Cl, H chains] [Fischer projection 2: HOH₂C, COOH, H, OCH₃ configurations] (5) (c) Draw and label the E and Z isomers for each of the following compounds. (5) (d) Draw the structure of (Z)-3-isopropyl-2-heptene. (2) (20)
Q. 4. (a) In benzaldehyde, two of the ring protons have resonance at 7.87 ppm, and the other three have resonance in the range from 7.5 to 7.6 ppm. Explain. (4 x 5 = 20) (b) Arrange the following protons in the decreasing order of their δ values in ¹H-NMR and account for your order: Methyl, ethylenic, acetylenic, aryl and aldehydic. (c) List the solvents most commonly used in IR spectroscopy. Why water and ethanol are not suitable solvents? (d) The UV spectrum of acetone shows absorption maxima at 166, 189, and 279 nm. What type of transition is responsible for each of these bands? (e) What types of electronic transitions are possible for each of the following compounds? (i) Cyclopentene, (ii) Acetaldehyde, (iii) Dimethyl ether, (iv) Methyl vinyl ether.
Q. 5. (a) Write down the reagents, conditions and mechanisms of the following reactions: (10) i). Kolbe reaction. ii). Williamson synthesis iii). Dow Process iv). Reimer-Tiemann reaction v). Bromination of phenol (b) Outline all steps involved in the synthesis of the following compounds from benzene or toluene, assuming that the ortho / para mixtures are separable: (10) (20) i). n-Butylbenzene ii). m-Nitrotoluene iii). p-Bromonitrobenzene iv). p-Bromobenzoic acid. v). 1,2-Dibromo-4-nitrobenzene
Q. 6. (a) Describe with equations all possible methods that can be used for the preparation of n-hexane. (10) (b) Why Corey-House Method is more suitable as compared to Wurtz reaction for the synthesis of alkane. Explain with examples. (5) (c) Draw the structures of following compounds and label them with IUPAC systematic rules: (5) (20) i). 3-cyclopentylhexane ii). 2-cyclobutyl-3-methylpentane iii). Isopropylcyclodecane iv). 2-methylbicyclo [3.2.0] heptanes v). 8-methylbicyclo [3.2.1] octane
Q. 7. (a) How can you prepare each of the following substances by a reaction involving Grignard reagent? i). CH₃CH₂CHOHCH₃ (Two ways) ii). Cyclohexylcarbinol derivative / Benzyl alcohol analogue (Two ways) iii). (CH₃)₃CD iv). (CH₃CH₂)₃COH (Three ways) v). Substituted secondary/tertiary alcohol configuration (5) (b) How will you bring about the following conversions? i). Malonic ester derivation to CH₃CH(COOC₂H₅)₂ pathway ii). Alkyl ester transformation to functionalized configurations like HOOC-CH₂-CH(CH₃)-CH₂-COOH (5) (c) How would you synthesize each of the following compounds by the Reformatsky reaction? [Structure i: β-hydroxy ester chain / Ethyl 3-hydroxy-3-methylpentanoate derivative] [Structure ii: Substituted β-hydroxy branched configuration] (5) (d) How would you synthesize each of the following compounds by the Wittig reaction? i). C₆H₅C(CH₃)=CH₂ ii). C₆H₅CH=CHC₆H₅ (2.5) (e) How will you synthesize each of the following substances by an acetoacetic ester synthesis? i. 3,4-dimethyl-2,5-hexanedione ii. 3-acetyl-5-hexanoic acid. (2.5) (20)
Q. 8. (a) Discuss the following topics. (6 each) 1. Prostaglandins 2. Terpenes (12) (b) Name the epimers of D-glucose. (4) (c) Clearly represent the most stable conformation of the pyranose form of each of the following sugars: (4) (20) (a) D-Galactose (b) D-Mannose (c) L-Mannose (d) L-Ribose
