Physical Chemistry: 3. Which of the following statements is true? A) The de Brog
ID: 926666 • Letter: P
Question
Physical Chemistry:
3. Which of the following statements is true?
A) The de Broglie wavelength of a He atom at 300 K is greater than that for an Ar atom at 300 K.
B) The de Broglie wavelength of a He atom at 300 K is greater than that for a He atom at 500 K.
C) Diffraction from a single slit involving Xe atom has not been observed because the de Broglie wavelength is too small.
D) Diffraction from a single slit involving Xe atom has not been observed because the de Broglie wavelength is too large.
A and C
4. Which of the following statements is true?
A) A diffraction pattern generated by an electron gun is formed by electrons interfering with one another.
B) The inability of classical theory to explain the spectral density distribution of a blackbody was called the ultraviolet catastrophe.
C) There is no upper limit to the photon energy that can be observed in the emission spectrum of the hydrogen atom.
D) Einstein explained the photoelectric effect by postulating that the energy of light depends on its frequency.
5. Which of the following statements is true?
A) A quantum mechanical system with discrete energy levels behaves as if it has a continuous energy spectrum if the energy difference between energy levels Esatisfies the relationship E < < kT.
B) A quantum mechanical system with discrete energy levels behaves as if it has a continuous energy spectrum if the energy difference between energy levels Esatisfies the relationship E >> kT.
C) If the energy levels can not be distinguished in an experiment, the system has a continuous energy spectrum from the viewpoint of the observer.
D) If the energy levels can be distinguished in an experiment, the system has a continuous energy spectrum from the viewpoint of the observer.
6.Which of the following statements is correct?
A) Because the de Broglie wavelength of a H2 molecule at 300. K is on the order of atomic dimensions, all properties of H2 are quantized.
B) For a H2 molecule moving in a one liter cubic container, the wavelength is much larger than the characteristic dimension of the container.
C) A system must be treated using quantum mechanics if the characteristic size for the property of interest is comparable to the wavelength.
D) The de Broglie wavelength of a H2 molecule is greater at 300. K than at 600. K.
Thank you!
B and C B and D A and DA and C
Explanation / Answer
(3) A and C
Because, wavelength, Lambda = h/mv, smaller the mass greater the wave length.
(4) B and D
(5) A and C
(6) A and C