1. Which of the following statement is false for mass spectroscopy?
a) Mass spectroscopy is used to identify unknown compounds within a sample, and to elucidate the structure and chemical properties of different molecules
b) Particle are characterized by their mass to charge ratios (m/z) and relative abundances
c) This technique basically studies the effect of ionizing energy on molecules
d) This technique can be used on all state of matter
Explanation: A mass spectrum measures the masses within a sample. Particles are characterized by their mass to charge ratios (m/z) and relative abundances. This technique basically studies the effect of ionizing energy on molecules and is applied to pure samples as well as complex mixtures. This technique is only possible to perform in the gaseous state.
2. Which of the following main component of mass spectroscopy deal with resolving the ions into their characteristics mass components according to their mass-to-charge ratio?
a) Ion Source
c) Detector System
d) Analyzer tube
Explanation: The complete process involves the conversion of the sample into gaseous ions, with or without fragmentation, which is then characterized by their mass to charge ratios (m/z) by an analyser. Eventually, the second analyzer will analyse fragment the selected ions and detect the ions emerging from the last analyzer and measure their and relative abundances with the detector that converts the ions into electrical signals.
3. Who discovered the mass spectrometer?
a) Francis Aston
b) J. J Thomson
c) Ernest O. Lawrence
d) Walter Kaufmann
Explanation: The mass spectrometer was invented by JJ THOMSON. He performed a series of experiments in 1897 designed to study the nature of electric discharge in a high-vacuum cathode-ray tube. Further modified by F. W. Aston shortly after World War I. He constructs the first velocity focusing mass spectrograph which has mass resolving power of 130.
4. In which state of matter mass spectroscopy is being performed?
Explanation: In the mass spectrometric analysis of compounds is firstly done by production of gas phase ions of the compound, basically by electron ionization. This molecular ion undergoes fragmentation.
5. A PMR spectrometer operates at 300 MHz. Find the value of magnetic field.
Given: gN = 5.585 and BN = 5.05 x 10-27 JT-I.
a) 7.05 T
b) 6.38 T
c) 7.58 T
d) 5.93 T
Explanation: According this formula of frequency:
The value of magnetic field is 7.05 T for PMR spectrometer operates at 300 MHz