This set of Solid State Chemistry Interview Questions and Answers for freshers focuses on “Survey of Techniques and their Applications to Solids”.
1. An X-ray powder diffraction pattern is a set of ______________
Explanation: An X-ray powder diffraction pattern is a set oflines or peaks, each of different intensity and position (d-spacing or Bragg angle, Θ) on either a strip of photographic film or a length of chart paper.
2. The line positions if the X-ray powder diffraction are_______________
Explanation: The line positions in the X-ray powder diffraction are fixed and are characteristics of that substance. The intensities may vary from sample to sample, depending on the method of sample preparation and the instrumental conditions.
3. What is the range of detecting lower limit of impurity phases in percentage?
a) 1 to 5
b) 10 to 20
c) 20 to 50
d) 50 to 70
Explanation: The powder X-ray diffraction method can be used as a rough check on purity provided the impurities are present as a separate crystalline phase(s). The lower limit of detection of impurity phases in routine work is usually in the range of 1 to 5 percent.
4. The amount of a particular crystalline phase in a mixture may be determined by which of the following method?
a) X-ray powder diffraction
b) Qualitative phase analysis
c) Quantitative phase analysis
d) X-ray powder refraction
Explanation: The amount of a particular crystalline phase in a mixture may be determined by Quantitative X-ray diffraction. The procedure is straightforward but somewhat tedious and prone to error.
5. In the quantitative analysis of a particular crystalline phase which of the following material is used as an internal standard?
Explanation: In the quantitative analysis of a particular crystalline phase it is neccasary to add an internal standard which is a well crystallized phase such as α-Al203, to the sample in a closely controlled amount ( e.g. 10 percent by weight)
6. The positions of the line in a powder pattern are governed by the values of which of the following____
a) parabolic cell parameters
b) circular cell parameters
c) line position cell parameters
d) unit cell parameters
Explanation: The positions (d- spacings) of the lines in a powder pattern are governed by the values of the unit cell parameters (a, b, c, α, β, ϒ). Unit cell lattice parameters are normally determined by single crystal methods but the values obtained are often accurate to only two or three significant figures.
7. If the composition of the solid solutions dependence is linear then which of the following law is obeyed?
a) Mendeleev’s law
b) Stock Barger’s law
c) Bridgeman’s law
d) Vegard’s law
Explanation: for the solid solutions the composition dependence if linear then Vegard’s law is obeyed, deviation from this law often occur in metallic solid solutions and when they occur can usually be ascribed to a structural feature in the solid solutions.
8. Which of the following statements is appropriate for the crystalline solids?
a) They give diffraction pattern of broad humps
b) They give diffraction pattern of sharp lines
c) They have circular line positions
d) They have parabolic line positions
Explanation: Crystalline solids give diffraction patterns that have a number of sharp lines. However non-crystalline solids like-glasses, gels give diffraction patterns that have a small number of very broad humps.
9. High temperature X-ray diffraction is a valuable technique for obtaining ___________
a) Functional information on polymers
b) Structural information on polymorphs
c) Concentration of polymers
d) Solubility of polymers
Explanation: High temperature X-ray diffraction is a valuable technique for obtaining the structural information on polymorphs and phases that exist only at high temperatures. It is particularly useful for studying high temperature structures at cannot be preserved to room temperature by quenching.
10. For the single crystal X-ray diffraction studies what is the length of the diameter that a single crystal should have?
Explanation: For the single crystal X-ray diffraction studies, it is necessary to have crystals that are at least 0.05 mm in diameter. Otherwise, the intensities of the diffracted beams are too weak to be detected clearly. This is because the efficiency with which X-rays are diffracted is very low.
Sanfoundry Global Education & Learning Series – Solid State Chemistry.
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