GUIDE QUESTIONS WITH ANSWERS GRADED
A+
● What is the full form of LASER? Answer: Light Amplification by
Stimulated Emission of Radiation
● What is the time between successive electromagnetic wave maximum
for light of wavelength 500 nm? Answer: 1.6 x 10^-15 sec
● How many kilojoules per mole in the energy of NO2 increased when it
absorbes infrared radiation with a wavenumber of 2300 cm-1?
Plank constant (h) = 6.626 x 10-34 J.s
Avogadro number = 6.023 x 1023
Speed of light (c) = 2.997 x 108 m/s Answer: 27.7 kJ/mol
● What is the difference between the Raman and Raleigh scattering?
Answer: Raman is the inelastic scattering of light whereas Rayleigh is an
elastic scattering of right.
● Which one is the following statement is correct?
,a) Energy is conserved in both the Stokes Raman and Rayleigh
scattering.
b) The molecule gain energy in Rayleigh scattering but loses in anti-
stokes Raman scattering.
c) The molecule loses energy in stokes scattering but gain energy in anti-
stokes Raman scattering.
d) The molecule gains energy in stokes scattering but loses energy in
anti-stokes Raman scattering.
e) None of the above Answer: c
● What kind of lamps you would use as source of 250 and 800 nm
wavelengths? Answer: D2 lamp for 250 and tungsten lamp for 800 nm.
● Which one is the correct order of sensitivity from lowest to highest for
3 different detectors?
i) photomultiplier tube > charge couple device > photodiode array
ii) charge couple device > photodiode array > photomultiplier tube
iii) photomultiplier tube < charge couple device < photodiode array
iv) photodiode array < photomultiplier tube < charge couple device
v) photomultiplier tube < photodiode array < charge couple device
Answer: iv
● State the four advantage of the inductively coupled plasma compared
with a flame in atomic spectroscopy Answer: 1. No self-absorption
, 2. High and homogeneous flame
3. Avoid oxide and hydroxide formation
4. Low background noise
● The doppler line-width can be expressed as:
δ λ = λ (7 x 10-7) Squareroot(T/M)
What is the line-width of Fe (atomic mass is 56) at emission line near
300 nm at 2227 degrees C? Answer: 0.0014 nm
● The following equation describes the Boltzmann distribution in
relative population of different states at thermal equilibrium:
N*/ N = (g*/g) e^ − Δ E k T
The lowest excited state of a sodium atom lies 5.39 x 10-19 J/atom
above the ground state. The degeneracy of the excited and ground states
are 5 and 2, respectively. What is fraction of Na excited at 2600 K?
Answer:
● Which one of the following statement is correct?
a. The state in which the electron spins are opposite is called a triplet
state.
b. The state in which the electron spins are parallel is called a singlet
state.
c. The state in which the electron spins are parallel is called a triplet
state.