BT-101 Engineering Chemistry - Dec 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDefine Hardness of water. Explain the various units of hardness and their inter-relationship. Why is EDTA method preferred over other methods for hardness determination?
   How to answer

   • Definition of hardness as CaCO3 equivalent due to Ca and Mg salts
   • Units: ppm, mg/L, degree Clark, degree French and their inter-relations
   • Temporary vs permanent hardness concept
   • Reasons for EDTA preference: stability, selectivity, sharp end point, versatility
2. 7 Marks
   bExplain the principle of EDTA titration. Calculate the total hardness (in ppm) of a water sample containing: $Ca(HCO_{3})_{2}=16.2$ mg/L, $Mg(HCO_{3})_{2}=7.3$ mg/L, $MgCl_{2}=9.5$ mg/L and $CaSO_{4}=13.6$ mg/L.
   How to answer

   • Principle of complexometric EDTA titration with EBT indicator
   • Stability of metal-EDTA complexes and pH 9-10 buffer role
   • Formula for total hardness as CaCO3 equivalent
   • Calculation for given Ca and Mg salts to get ppm value
3. 7 Marks
   aCompare Zeolite and Ion-Exchange processes for water softening. Discuss why Ion-Exchange is superior for high-pressure boilers.
   How to answer

   • Principle of Zeolite / permutit process and its reactions
   • Principle of ion-exchange resins: cation and anion exchangers
   • Comparison on hardness removal, silica, suitability
   • Reason for ion-exchange superiority for high-pressure boilers: zero hardness, demineralization
4. 7 Marks
   bWhat is Desalination? Describe the Reverse Osmosis (RO) process with a neat labeled diagram. State its industrial applications.
   How to answer

   • Definition of desalination
   • Principle of reverse osmosis vs natural osmosis
   • Neat labeled diagram of RO cell with semipermeable membrane and applied pressure
   • Industrial applications: drinking water, brackish water, boiler feed
5. 7 Marks
   aWhat is periodic table? Write trends of following in a group and in a period giving suitable reasons: i) electronegativity ii) electron affinity iii) atomic size
   How to answer

   • Definition / layout of periodic table
   • Trend of electronegativity in group and period with shielding and nuclear charge reasons
   • Trend of electron affinity in group and period with reasons
   • Trend of atomic size in group and period with reasons
6. 7 Marks
   bWrite brief note on (any two): i) Effective nuclear charge ii) Polarizability iii) Oxidation states
   How to answer

   • Concept of effective nuclear charge with formula and variation
   • Concept of polarizability and factors affecting it
   • Concept of oxidation states and periodic variation
   • Any two to be covered concisely with examples
7. 7 Marks
   aDiscuss the mechanism of Addition and Condensation polymerization with one example each. Define "Functionality" of a monomer.
   How to answer

   • Free-radical / ionic mechanism steps of addition polymerization with example
   • Mechanism steps of condensation polymerization with example
   • Definition of functionality of monomer
   • Relation of functionality to linear vs cross-linked polymer
8. 7 Marks
   bWrite the synthesis, properties and engineering uses of: i) Bakelite ii) PMMA iii) Neoprene
   How to answer

   • Monomers and reaction for Bakelite, PMMA, Neoprene synthesis
   • Key properties: thermal, mechanical, chemical resistance
   • Engineering uses of each polymer
   • Reaction schemes / structures
9. 7 Marks
   aDefine Lubrication. Explain the mechanism of Extreme Pressure Lubrication. Which type of lubricants are used for heavy-duty machinery?
   How to answer

   • Definition of lubrication and friction concept
   • Mechanism of extreme pressure lubrication with additive film formation
   • Types of EP additives and lubricants used
   • Suitability for heavy-duty machinery under high load and temperature
10. 7 Marks
    bDiscuss the importance of Viscosity Index. How does it affect the performance of an engine oil in varying temperatures?
    How to answer

    • Definition of viscosity index
    • Effect of temperature on viscosity and VI scale
    • Importance of high VI for engine oil performance
    • Behaviour in varying temperatures: cold start vs high temperature
11. 7 Marks
    aState the selection rules for IR Spectroscopy. Explain why some molecules are "IR Active" and some are not. Describe the various types of molecular vibrations.
    How to answer

    • Selection rule: change in dipole moment during vibration
    • Explanation of IR active vs IR inactive with examples like HCl vs O2
    • Stretching vibrations: symmetric and asymmetric
    • Bending vibrations: scissoring, rocking, wagging, twisting
12. 7 Marks
    bExplain the principle of Thin Layer Chromatography (TLC). How is the $R_{f}$ value calculated and what does it indicate?
    How to answer

    • Principle of adsorption and partition on TLC plate
    • Procedure: spotting, development, visualization
    • Formula $R_{f}$ = distance solute / distance solvent
    • Significance of $R_{f}$ for identification and purity
13. 7 Marks
    aExplain the "Differential Aeration Theory" of corrosion with the help of Pitting Corrosion example. Why do iron nails rust faster in saline water?
    How to answer

    • Concept of differential aeration: oxygen concentration cell
    • Pitting corrosion mechanism with anodic pit and cathodic surroundings
    • Reactions at anode and cathode
    • Reason for faster rusting in saline water: conductivity and electrolyte role
14. 7 Marks
    bWhat is Sacrificial Anodic Protection? How is it used to protect underground pipelines? Compare it with Impressed Current Cathodic Protection.
    How to answer

    • Definition of sacrificial anodic protection
    • Application to underground pipelines with Mg/Zn anodes
    • Principle of impressed current cathodic protection
    • Comparison on power need, maintenance, cost and applicability
15. 7 Marks
    aExplain the chemical reactions involved in the Lime-Soda process. Why is a small amount of coagulant (like Alum) often added during this process?
    How to answer

    • Lime reactions for temporary Ca and Mg hardness
    • Soda reactions for permanent hardness
    • Equations for Ca(HCO3)2, Mg(HCO3)2, MgSO4, CaCl2 removal
    • Role of coagulant like alum in settling fine precipitates
16. 7 Marks
    bWhat is lime-soda process? Calculate the requirement of Lime (80% pure) and Soda (90% pure) for treatment of 1,00,000 liters of water containing: $Ca(HCO_{3})_{2}=40.5$ ppm, $Mg(HCO_{3})_{2}=36.5$ ppm, $MgSO_{4}=30$ ppm and $CaCl_{2}=22.2$ ppm.
    How to answer

    • Definition of lime-soda process
    • Formulae for lime and soda requirement as CaCO3 equivalent
    • Calculation for given salts with purity correction
    • Final lime (80% pure) and soda (90% pure) quantities for 1,00,000 L