Application Of Spectroscopy

(i) In which region of the electromagnetic spectrum does an absorption at 600 nm come ?

1. Near -UV
2. Infrared
3. Vacuum -UV
4. Visible

(ii) What does the notation σ*←n mean ?

1. Absorption: transition from a non-bonding MO to σ* MO
2. Absorption: transition from a quantum level n to σ* MO
3. Emission: transition from a quantum level n to σ* MO
4. Emission: transition from a non-bonding MO to σ* MO

(iii) Which molecule or ion has D_3h symmetry ?

1. [H₂O]⁺
2. CHCl₃
3. [CO₃]^2-
4. NF₃

(iv) Which of othe following statements regarding NMR spectroscopy is wrong ?

1. NMR signals towards the left of the spectral chart correspond to larger chemical shifts
2. Chemical shifts are larger when the frequencies of the radiation which induces the nuclear transi- tions are higher
3. Chemical shifts are larger when shielding effects are greater.
4. A hydrogen signal splits into n-1 peaks by spin-spin coupling when the number of equivalent hydrogen atoms on adjacent atoms (s) is n. and no other neighbouring atoms are involved.

(v) Which of (a)-(d) indicates the correct order of carbon chemical shifts of the four carbons of the following compound

1. C_Me < C2 < C3 < C1
2. C_Me < C3 < C2 < C1
3. C_Me < C2 < C1 < C3
4. C_Me < C1 < C2 < C3

(vi) How many signals does the aldehyde (CH₃)₃ CCH₂CHO have in ¹H NMR and ¹³C NMR spectra ?

1. Five ¹H signals and six ¹³C signals
2. Three ¹H signals and four ¹³C signals
3. Five ¹H signals and four ¹³C signals
4. Three ¹H signals and six ¹³C signals

(vii) Which hydrogen of 1-chloropent-2-ene shows the largest chemical (downfield) shift in its NMR spectrum

1. The h on c1
2. The h on either c2 or c3
3. The h on c4
4. The h on c5

(viii) An NMR transmitter consists of:

1. Frequency synthesizer, RF signal generator, trans- mitter controller and receiver
2. CPU, RF signal generator, transmitter controller, and RF amplifier
3. Frequency synthesizer, RF signal generator, and transmitter controller
4. Frequency synthesizer, RF signal generator, trans- mitter controller, and RF amplifier

(ix) Samples prepared for Moessbauer spectroscopy should be in which phase ?

1. Any phase
2. Liquid
3. Solid
4. Vapour

(x) The correct value of isomer shift (in Mossbauer spectra) and its explanation for Fe (II) - TPP and Fe (III) - TPP respectively from the following are : (TPP = Tetraphenyl porphyrinate)

1. 0.52mms-1
2. 0.45mms-1