🔵 Section A – Fill in the Blanks (10 × 2 = 20 marks)
Q1. Attempt any 10 parts.
(i) The Lead-Acid battery is an example of secondary battery while Zn-MnO₂
Dry cell is a primary type of battery.
(ii) Standard Hydrogen Electrode consists of Pt metal electrode and
arbitrarily assigned 0 V potential.
(iii) The standard electrode potential determined under standard conditions,
refers to:
Cu2+∣Zn2+∣∣Zn∣Cu\text{Cu}^{2+} | \text{Zn}^{2+} || \text{Zn} | \
text{Cu}
E.M.F. and T = 298 K.
(iv) The permanent hardness of water is caused due to CaSO₄ and MgCl₂
salts present in water.
(v) The full form of EDTA is Ethylene Diamine Tetraacetic Acid, and it is
used in determination of water hardness.
(vi) The pH for potable water should be in the range of 6.5 to 8.5, and total
hardness of the potable water should be less than 150 ppm.
(vii) A semipermeable membrane allows solvent to pass through it, but not
solutes.
(viii) The crystalline polymers have sharp peaks in their X-ray diffraction
pattern, while amorphous polymers have no sharp peaks.
(ix) Silk is a natural fiber while Polyester is a synthetic fiber.
(x) FTIR refers to Fourier Transform Infrared and DTA refers to
Differential Thermal Analysis.
(xi) The n→π* and π→π* transitions occur in UV-Visible spectroscopy and
stretching and bending vibrations in IR.
(xii) Polyethylene is formed by addition polymerization while Bakelite is
formed by condensation polymerization.
(xiii) The Lead-acid storage battery has Anode made up of Pb, and Cathode
made up of PbO₂.
🟠 Section B – Short Answer Questions (8 × 5 = 40 marks)
Q2. Attempt any 8 parts.
i. What is scale and sludge formation in boilers?
Scale: Hard, adherent deposits due to CaSO₄, Mg(OH)₂.
Sludge: Soft, loose deposits (e.g., CaCl₂, MgCl₂).
Harm: Decreases heat transfer, leads to overheating, corrosion, and
bursting.
ii. What is Standard Hydrogen Electrode (SHE)?
Reference electrode with H₂ gas at 1 atm and H⁺ at 1M, Pt electrode.
Its potential is defined as 0 V.
Used to measure other electrode potentials.
iii. Difference between crystalline and amorphous polymers:
Crystalline: Sharp XRD peaks, strong IMFs, rigid.
Amorphous: No clear structure, flexible, no peaks.
iv. Define number average and weight average molecular weight:
Number average (Mn): Mn=ΣNiMiΣNiM_n = \frac{\Sigma N_i M_i}{\
Sigma N_i}
Weight average (Mw): Mw=ΣNiMi2ΣNiMiM_w = \frac{\Sigma N_i
M_i^2}{\Sigma N_i M_i}
v. What is a Zeolite?
Microporous aluminosilicates.
Used as ion-exchangers to remove hardness-causing Ca²⁺ and Mg²⁺
ions from water.
vi. Glass Transition Temperature (Tg):
The temperature at which amorphous polymers become soft and
rubbery.
Below Tg – hard & brittle; above Tg – flexible.
Important for selecting polymer use conditions.
vii. UV-Visible spectroscopy principle:
Absorption of UV or visible light causes electronic transitions (π→π*,
n→π*).
Applications: concentration determination, structural analysis.
viii. Lime-soda calculation (brief concept):
Lime (Ca(OH)₂) and soda (Na₂CO₃) used to precipitate hardness salts.
Reactions remove Ca²⁺ and Mg²⁺ ions from water. (You’d show steps in
exam.)
ix. Standard Cell potential calculation:
Given:
EAg+/Ag∘=+0.80 V,ESn2+/Sn∘=−0.14 VE^\circ_{\text{Ag}^+/\text{Ag}} =
+0.80\text{ V}, \quad E^\circ_{\text{Sn}^{2+}/\text{Sn}} = -0.14\
text{ V}
Ecell∘=Ecathode∘−Eanode∘=0.80−(−0.14)=0.94 VE^\circ_{\text{cell}} =
E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} = 0.80 - (-0.14) = 0.94\
text{ V}
x. Reverse Osmosis principle:
Water is forced through a semipermeable membrane under high
pressure.
Removes ions, salts, impurities.
xi. Free radical chain polymerization:
Steps:
1. Initiation: Free radical generation.
2. Propagation: Radical reacts with monomer to form a chain.
3. Termination: Radicals combine to end the chain.
Example: Polymerization of ethylene to form polyethylene.
🟢 Section C – Long Answer Questions (4 × 10 = 40 marks)
Q3. Attempt any 4 parts.
i. Nernst Equation Derivation:
For single electrode potential:
E=E∘−0.0591nlog[Products][Reactants]E = E^\circ - \frac{0.0591}{n} \log \
frac{[Products]}{[Reactants]}
For half-cell:
Mn++ne−⇌M\text{M}^{n+} + ne^- \rightleftharpoons \text{M}
E=E∘−0.0591nlog[Mn+]E = E^\circ - \frac{0.0591}{n} \log [\
text{M}^{n+}]
ii. Degree of Polymerization:
Number of repeating units in a polymer chain.
Polymerization Technique for High Purity:
o Condensation polymerization (step-growth)
o Addition polymerization
o Use of controlled conditions, initiators, catalysts.
iii. Hard Water & Ion Exchange Method:
Contains Ca²⁺, Mg²⁺ ions.
Hardness Measurement: in ppm.
Ion Exchange Process:
o Uses resins that exchange Na⁺ or H⁺ with Ca²⁺, Mg²⁺
o Softens water by removing hardness ions.
iv. Battery & Lithium-Ion Battery Construction:
Electrochemical device to convert chemical to electrical energy.
Li-Ion Battery:
o Anode: Graphite
o Cathode: LiCoO₂ or LiFePO₄
o Electrolyte: Lithium salt in organic solvent
o Working: Li⁺ ions shuttle between electrodes during
charge/discharge.
v. Differential Scanning Calorimetry (DSC):
Measures heat flow with temperature.
Used to detect Tg, melting point, crystallinity.
Applications in material identification, polymer analysis, etc.
vi. Five Water Quality Parameters:
1. pH – acidity/alkalinity
2. TDS – total dissolved solids
3. Hardness – Ca²⁺, Mg²⁺ content
4. Turbidity – suspended particles
5. DO/BOD – dissolved & biological oxygen demand
vii. Principles of Green Chemistry:
Prevent waste
Atom economy
Less hazardous chemicals
Renewable feedstocks
Safer solvents, etc.
Examples:
Using H₂O₂ instead of KMnO₄
Microwave synthesis without solvents
