UV SPECTROSCOPY CSIR-NET GATE PREVIOUS YEAR QUESTIONS

Previous year CSIR-NET, GATE questions on UV-Visible Spectroscopy

1. UV SPECTROSCOPY ADRIJA D I210501

2. 1. Given the fact that 1,3-butadiene has a UV absorption of 217 nm, the absorption wavelength (in nm) for the conjugated system shown below is ___ Solution : Basic value = 217 nm Ring residue = 20 nm Exocyclic double bond = 15 nm Extended conjugation = 30 nm max = 249 nm 2

3. 2. In the UV – V is spectrum, a diterpenoid exibted a max at 275 nm. The compound among the choices given below, is - 3

4. Solution : A) Basic value ( transoid ) = 214 nm Ring residue = 15 nm Alkyl residue = 5 nm Exocyclic double bond = 5 nm max = 239 nm C) Basic value ( Cisoid ) = 253 nm Ring residue = 10 nm Alkyl residue = 5 nm Exocyclic double bond = 5 nm max = 273 nm D) Basic value ( Cisoid ) = 214 nm Ring residue = 15 nm Alkyl residue = 10 nm Exocyclic double bond = 10 nm max = 249 nm 4