BSc Third Year (Sem 5 & 6) Chemistry – Daily Revision MCQ (English Medium)
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A strong, sharp IR absorption near 1715 cm⁻¹ is characteristic of which bond vibration?
Chapter 2: Infrared Spectroscopy
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Answer: B. C=O stretching (saturated ketone)
Carbonyl stretching of a simple ketone appears near 1715 cm⁻¹; O–H stretch lies around 3200–3600 cm⁻¹ and C≡N near 2250 cm⁻¹.Which compound is used as the internal reference (δ = 0 ppm) in ¹H NMR spectroscopy?
Chapter 3: NMR Spectroscopy
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Answer: D. Tetramethylsilane (TMS)
TMS, Si(CH₃)₄, gives one sharp signal from 12 equivalent, highly shielded protons, so it is set as δ = 0.What is the crystal field stabilisation energy (CFSE) of a d³ ion in an octahedral field?
Chapter 5: Crystal Field Theory
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Answer: A. −1.2 Δo
d³ in octahedral field = t₂g³; each t₂g electron contributes −0.4 Δo, so CFSE = 3 × (−0.4 Δo) = −1.2 Δo.What is the spin-only magnetic moment of a complex ion with 3 unpaired electrons?
Chapter 6: Electronic Spectra and Magnetic Properties of Complexes
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Answer: C. 3.87 BM
μ = √(n(n + 2)) = √(3 × 5) = √15 ≈ 3.87 BM (1.73, 2.83 and 4.90 are for 1, 2 and 4 unpaired electrons).The lanthanide contraction is mainly caused by:
Chapter 7: Lanthanides and Actinides
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Answer: B. Poor shielding of the nuclear charge by 4f electrons
Across the series nuclear charge rises by one each step, but the diffuse 4f orbitals shield it poorly, so the atomic and ionic radii steadily decrease.A radioactive isotope has a half-life of 5 days. How much of an 80 g sample remains after 15 days?
Chapter 10: Nuclear Chemistry
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Answer: A. 10 g
15 days = 3 half-lives, so the amount left = 80 × (1/2)³ = 80/8 = 10 g.Which metal ion is present at the centre of the chlorophyll molecule?
Chapter 11: Bioinorganic Chemistry
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Answer: D. Mg²⁺
Chlorophyll is a magnesium porphyrin; iron is the central metal in haemoglobin and cobalt in vitamin B₁₂.Which of the following is a non-reducing sugar?
Chapter 12: Carbohydrates
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Answer: C. Sucrose
In sucrose the anomeric carbons of glucose (C1) and fructose (C2) are joined in the glycosidic bond, so no free hemiacetal group is left to reduce Fehling's or Tollens' reagent.Which standard amino acid is optically inactive because it has no chiral carbon?
Chapter 13: Amino Acids and Proteins
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Answer: A. Glycine
In glycine (H₂N–CH₂–COOH) the α-carbon carries two hydrogen atoms, so it is not a stereocentre.Nylon-6,6 is prepared by condensation polymerisation of:
Chapter 15: Polymers
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Answer: D. Hexamethylenediamine and adipic acid
Hexamethylenediamine (6 C) and adipic acid (6 C) join through amide links, hence '6,6'; caprolactam gives nylon-6, glycol + terephthalic acid gives PET, phenol + formaldehyde gives Bakelite.
BSc Third Year (Sem 5 & 6): MCQ in other subjects
All questions are written by PadhaiNotes in our own words from the common syllabus of Maharashtra universities (NEP). Your own university's syllabus may differ a little.