Q. In a 400 MHz 1H NMR spectrometer, a proton resonates at 1560 Hz higher than that of tetramethylsilane. The chemical shift value of this proton is___________ppm. (Round off to one decimal place) (Chemical shift of tetramethylsilane is fixed at zero ppm) Solution: The chemical shift of Nuclear Magnetic Resonance Spectroscopy is the relative resonant […]

Q. Consider a system of three identical and distinguishable non-interacting particles and three available nondegenerate single particle energy levels having energies 0, e and 2e. The system is in contact with a heat bath of temperature T K. A total energy of 2ɛ is shared by these three particles. The number of ways the particles

Q. Consider a two-state system at thermal equilibrium having energies 0 and 2kBT for which the degeneracies are 1 and 2, respectively. The value of the partition function at the same absolute temperature T is ______.  (Round off to two decimal places) (kB is the Boltzmann constant) Solution: General formula is q = Ʃ gi e-Ei / KT, For

Q. The entropy change for the melting of ‘x’ moles of ice (heat of fusion is 80 cal g–1) at 273 K and 1 atm pressure is 28.80 cal K–1. The value of ‘x’ is___________. (Round off to two decimal places) (Molecular weight of water =18 g/mol) Solution: Δ S = Δ H/ T , OR  Δ

Q. An ideal gas occupies an unknown volume V liters (L) at a pressure of 12 atm. The gas is expanded isothermally against a constant external pressure of 2 atm so that its final volume becomes 3 L. The work involved for this expansion process is______cal. (Round off to two decimal places) (Gas constant R

Q. On heating a sample of 25 mg hydrated compound (molecular weight = 250 g/mol) in thermogravimetric analysis, 16 mg of dehydrated compound remains. The number of water molecules lost per molecule of hydrated compound is                                                                             . (Molecular weight of water = 18 g/mol) Solution: 25 mg Compound contains (25-16) g of Water = 9

Q. The number of 1H NMR signals observed for the following compound is Ans: The number of 1H NMR signals observed for the following compound is 6 Solution: Enantiotropic protons are protons that are replaced by another group of protons. They have the same mirror image and chemical shift in the NMR spectrum. Therefore, Here

Q. The number of following diene(s) that undergo Diels-Alder reaction with methyl acrylate is Ans: The number of following diene(s) that undergo Diels-Alder reaction with methyl acrylate is 5 Solution: Diels- Alder Reaction is a  pericyclic chemical reaction between substituted alkenes or Dienophiles and conjugated dienes.  Here, all the cis structures will undergo Diels- Alder Reaction

Q. Among the following compounds, the number of compounds that DO NOT exhibit optical activity at room temperature is Ans: 4 ​Among the following compounds, the number of compounds that DO NOT exhibit optical activity at room temperature is 4.

Q. In the following reaction, the stereochemistry of the major product is predicted by the (A) Cram’s model (B) Cram’s chelation model (C) Felkin model (D) Felkin-Anh model Ans: Cram’s chelation model