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CH-2
Dr. Vikram Panchal
Institute Of Chemistry
Worksheet: -2: Energy, Quantum no and Pauli’s principle
1. One quantum is absorbed per molecule of gaseous iodine for converting into iodine atoms. If
light absorbed has wavelength of 5000 A. Calculate the energy required in KJ mol-1 (Equation:
I2(s) 2I(g)
(Bond dissociation enthalpy of iodine: 151 KJ/mole)
2. A near ultraviolet photons of 300 nm is absorbed by a gas and then re-emitted as two photon.
One photon is red with wavelength 760 nm. What would be the wavelength of the second photon?
3. Electromagnetic radiation of wavelength 242 nm is just sufficient to ionize the sodium atom.
Calculate the ionisation energy of sodium in KJ mol-1. (Equation: Na(s)  Na+ + e- )
4. A 25 watt bulb emits monochromatic yellow light of wavelength of 0.57m.Calculate the rate of
emission of quanta per second.
5. Calculate the energy associated with the first orbit of Li2+. (Z=3 )
6. Neon gas is generally used in the sign boards. If it emits strongly at 616nm. Calculate
(a) The frequency of emission
(b) Energy of quantum
7. In astronomical observations, signals observed from the distant stars are generally weak. If the
photon detector receives a total of 3.15 x 10-18 J from the radiations of 600 nm. Calculate the
number of photons received by the detectors.
8. Given this set of quantum numbers for a multi-electron atom 2, 0, 0,1/2 and 2,0,0,-1/2. What is
the next highest allowed set of ‘n’ and ‘l’quantum numbers for this atom in its ground state?
9. The following quantum numbers are responsible for how many orbitals? Given: n=3, l=2, m=2
10. With increasing quantum number, the energy difference between adjacent levels of hydrogen
atom ___________. (increases/decreases)
11. A laser used to read CDs emit red light wavelength 700 nm. How many photons does it emit
each second if its power is 1.0 W?
12. The ionization enthalpy of hydrogen atom is 1.312 x 106 Jmol-1. The energy required to excite
the electron in the atom from n=1 to n=2 is ________.
Sem-1
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