MCQs Test Based on Previous Year Question Paper B.Sc. VI Semester

Solution
The equation represents both Beer’s Law and Lambert’s Law.

The order of energy required for various transitions is: σ → σ* > n → σ* > π → π* > n → π*. This is because sigma bonds are generally stronger and require more energy to break compared to pi bonds.

The term “K-band” is associated with conjugated systems, and its appearance indicates the presence of extended π networks within a molecule. K-bands in UV-visible spectroscopy specifically refer to absorption bands arising from π → π* transitions in conjugated systems.

Homoannular diene, also known as a cisoid diene, in UV-Vis spectroscopy is 253 nm.

The extinction coefficient increases with both conjugation and chromophore length. Longer conjugated systems and larger chromophores generally lead to higher absorption intensity and thus, a larger extinction coefficient. 

Your calculation is spot on! You’re applying Woodward-Fieser rules to estimate the λmax (lambda max) for a conjugated diene system. Here’s a breakdown for clarity:

• Base value for a homoannular diene = 253 nm
• Alkyl substituents (4 total) = 4 × 5 = 20 nm
• Exocyclic double bonds (2 total) = 2 × 5 = 10 nm
• Additional conjugated double bond = 30 nm

Estimated λmax = 253 + 20 + 10 + 30 = 313 nm

(C) 15 μm to 200 μm ✅

This range is part of the infrared spectrum and is typically used in applications like thermal imaging, molecular vibration studies, and astronomy.

Correct answer: (C) X-ray > UV > Visible > IR ✅

Explanation: Frequency decreases from X-rays to IR.

Correct answer: (D) All of these ✅

Short explanation: IR spectroscopy can identify amide, carbonyl, and nitro groups based on their characteristic absorption bands.

Amides typically show a strong carbonyl stretch around 1640–1690 cm⁻¹ and an N-H stretch around 3200–3400 cm⁻¹.

Carbonyl groups (like in aldehydes, ketones, carboxylic acids, etc.) generally absorb around 1725 cm⁻¹.

Nitro groups often have strong asymmetric and symmetric stretching bands around 1500–1600 cm⁻¹ and 1300–1350 cm⁻¹.

Correct answer: (B) l and only ml ✅

Short explanation:
The angular wave function (also called the spherical harmonics part) of the hydrogen atom depends only on the azimuthal quantum number (l) and the magnetic quantum number (ml) — not on the principal quantum number (n), which affects only the radial part.

Correct answer: (C) Single valued and continuous ✅

Short explanation:
An acceptable wave function must be single-valued (i.e., the wave function must have only one value for each point in space) and continuous (i.e., it should not have any sudden jumps or discontinuities). This ensures the wave function is physically meaningful.

Correct answer: (B) Waves ✅

Short explanation:
The motion of a wave-particle (like an electron) is similar to waves because it exhibits both particle-like and wave-like properties, a concept known as wave-particle duality.

Correct answer: (B) de Broglie ✅

Short explanation:
The concept of matter waves was suggested by Louis de Broglie in 1924, proposing that particles, like electrons, have wave-like properties.

Correct answer: (C) Matter has wave-like properties ✅

Short explanation:
The main point of de Broglie’s equation is that matter (such as electrons) exhibits wave-like properties, a concept central to wave-particle duality.

Correct answer: (A) Position and momentum ✅

Short explanation:
Heisenberg’s uncertainty principle states that the position and momentum of a quantum particle cannot both be precisely determined at the same time. The more accurately one is measured, the less accurately the other can be known.

Correct answer: (C) Phase velocity ✅

Short explanation:
The energy of a wave divided by its momentum gives the phase velocity, which describes the speed at which the wave’s phase propagates through space.

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