Bihar Engineering University, Patna

B.Tech 2nd Semester Examination - 2026

Time: 03 HoursCode: 100215Full Marks: 70

Q.1 Choose the correct option / answer the following (Any seven question only):[2×7=14]

The shape of the ammonia (NH₃) molecule according to VSEPR theory is?
1. Trigonal planar
2. Linear
3. Trigonal pyramidal
4. Tetrahedral
Which of the following metal carbonyls obeys the 18-electron rule?
1. Fe(CO)₅
2. Ni(CO)₄
3. Cr(CO)₄
4. Mn(CO)₂
UV-Visible spectroscopy mainly involves transitions of
1. Nuclear spins
2. Core electrons only
3. Protons only
4. Valence electrons
The resonance frequency, in NMR spectroscopy depends mainly on
1. Molecular weight
2. External magnetic field
3. Density
4. Melting point
The Nernst equation is used to determine
1. Rate of reaction
2. Heat of reaction
3. Molecular weight
4. Cell potential under non-standard conditions
Which electrolyte is used in a lead-acid battery?
1. NaOH
2. Dilute H₂SO₄
3. HCl
4. KOH
Temporary hardness of water is mainly due to
1. Calcium chloride
2. Magnesium sulfate
3. Sodium chloride
4. Calcium bicarbonate
Which process removes hardness by exchanging Ca²⁺ and Mg²⁺ ions with Na⁺ ions?
1. Lime-soda process
2. Zeolite process
3. Distillation
4. Reverse osmosis
Which polymer is an example of a thermoplastic?
1. Bakelite
2. Melamine
3. Polyethylene
4. Epoxy resin
Silicones are classified as
1. Natural polymers
2. Condensation monomers
3. Biopolymers
4. Inorganic polymers

Q.2

Discuss the Photoelectric Effect and Heisenberg's Uncertainty Principle with suitable examples.
[7]
Describe the formation of Molecular Orbitals using the Linear Combination of Atomic Orbitals. Draw and explain the molecular orbital diagram of O₂.
[7]

Q.3

Explain the principles of rotational and vibrational spectroscopy and applications of these techniques in structural elucidation of organic molecule.
[7]
Describe the principle, instrumentation, and applications of UV-Visible spectroscopy in chemistry.
[7]

Q.4

Derive the Nernst equation and explain its significance in determining the EMF of electrochemical cells under non-standard conditions.
[7]
Explain the mechanism of corrosion. Discuss different types of corrosion with suitable examples.
[7]

Q.5

What is hardness of water? Explain the types of hardness and describe the estimation of hardness by the EDTA method.
[7]
Discuss in details the Lime-Soda process for the removal of hardness of water.
[7]

Q.6

Differentiate between thermoplastics and thermosetting plastics. Discuss the preparation, properties and applications of commercially important thermoplastics such as Polyethylene, Polyvinyl Chloride and Polystyrene.
[7]
Describe the preparation, properties and applications of Phenol-Formaldehyde resin (Bakelite).
[7]

Q.7

Explain the Diels–Alder cyclization reaction and epoxide ring-opening reaction and their applications in organic synthesis.
[7]
Discuss the synthesis of aspirin from salicylic acid. Explain the reaction mechanism and significance of aspirin as an important pharmaceutical drug.
[7]

Q.8 Write Short note on:

Q.9 Write short note on any two of the following:[7×2=14]

Engineering Chemistry