This set of Solid State Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “The X-ray Diffraction Experiment”.
1. Which of the following variables govern the different X-ray techniques?
a) Radiation, sample, detector
b) Radiation, diffraction, detector
c) Heat, mass, proteins
d) Energy, sample, temperature.
Explanation: In the X-ray diffraction techniques the three variables govern it these are. Radiation-monochromatic or variable of λ. Sample-single crystal, powder or a solid piece, Detector-Radiation counter or photographic film.
2. Which of the following rays are used in the powder method of crystals?
a) Gamma rays
d) Monochromatic X-rays
Explanation: A monochromatic beam of X-rays strike a finely powdered sample that ideally has crystals randomly arranged in every possible orientation in the powder method.
3. In the powder method, in powder sample various _________ samples are also present in every possible orientation.
a) Miller indices
c) Unit cell
Explanation: Lattice planes are present in the powder sample in every possible orientation. For each set various lattice planes, therefore, at least some crystals must be oriented at the Bragg angle Θ, to the incident beam and thus diffraction occurs for these crystals and planes.
4. Which of the following method for detecting the diffracted beams in the powder method of crystals?
a) Miller method
b) Dalton method
c) Guinier method
d) Stockbarger method
Explanation: The diffracted beams in the powder method may be detected either by surrounding the sample with a strip of photographic film that is by and Debye-Scherrer and Guinier focusing methods or by using a movable detector, such as Geiger counter, connected to a chart recorder(diffractometer).
5. Which of the following shapes are formed by the diffracted radiation in the powder method?
Explanation: For any set of lattice phases, the diffracted radiation forms the surface of a cone. The only requirement for diffraction is that the planes be at angle Θ to the incident beam, no restriction is placed on the angular orientation of the plane about the axis of the incident beam.
6. In the powder method of the crystals if the Bragg’s angle is Θ then what is the angle of the cone formed by the diffracted beams?
Explanation: The diffracted beams in the powder method forms a cone, if the Bragg’s angle is Θ, then the angle between diffracted and undiffracted beams is 2Θ and the angle of the cone is 4Θ. Each set of planes gives its own cone of radiation.
7. During the detection of the cones by the thin strip of film which one of the following statements is appropriate for the cones and the films?
a) Cones are parallel to the strip of the films
b) Cones are perpendicular to the strip of the films
c) Cones intersects the strip of the films
d) Cones are vertically placed over the strip of the film
Explanation: In the powder method, the cones are detected by a thin strip of film wrapped around the sample, each cone intersects the film as two short arcs which are symmetrical about the two holes in the film(these allow entry and exit of an incident and undiffracted beams).
8. In the powder method during the detection of the cones, two arcs are produced by the cone, in a well-powdered method these arcs appear as a___________
d) Spotted lines
Explanation: During the detection of the cones in the powder method the cones intersects the strip of film as two short arcs, so in a well-powdered sample, each arcs appears as a continuous line, but in coarser samples the arcs may be spotty due to the relatively small number of the crystals present.
9. What is the disadvantage of the Debye-Scherrer film to obtain the d-spacings?
a) Temperature required is too high
b) Exposure time is long
c) Closely spaced arcs are circular
d) Cones formed by the diffracted beams are two heavy in weight
Explanation: The disadvantage of using Debye-Scherrer film method is that exposure times are long and that closely spaced arcs are not well resolved. This is because, although the incident beam enters the camera through a pinhole slit and collimator tube, the beam is somewhat divergent and the spread increases in the diffracted beams.
10. A convergent beam is obtained by placing which of the following material between the X-ray source and the sample?
a) Soil particles
b) Single crystal of carbon
c) Linear double crystal of graphite
d) Bent single crystal of quartz
Explanation: Convergent beam is obtained by placing a bent single crystal of quartz or graphite between the X-ray source and the sample. The orientation of this bent crystal is adjusted so that it diffracts the incident beam and converts it from the divergent beam into a convergent one.
Sanfoundry Global Education & Learning Series – Solid State Chemistry.
To practice all areas of Solid State Chemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.