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1. Mohs scale developed by German Mineralogist, Friedsich Mohs in 1822 can be used in the analysis of glass for measuring

  1. Hardness
  2. Refractive index
  3. Density
  4. Thickness

Answer: (1) Hardness

Explanation: In Mohs scale, the hardness of a substance is defined in terms of value between 1 to 10.

2. During forensic examination of glass, the edge thickness can be measured by

  1. Spherometer
  2. Micrometer
  3. Tapeko meter
  4. Spectrophotometer

Answer: (2) Micrometer

Explanation: Micrometer is a measuring instrument that has a calibrated screw that is widely used for accurate measurements of components.

3. Refractive index is the measure of:    

  1. Diffraction
  2. Refraction
  3. Reflection
  4. None of these

Answer: (2) Refraction

Explanation: The refractive index of glass is measured by immersion of glass in a liquid and that is why it is also called immersion method.

4. The Rf value depends upon which of the following factors?

  1. Solvent system employed
  2. Temperature
  3. Chamber saturation
  4. All of the above

Answer: (4) All of the above

Explanation: Factors affecting Rf values are:
-> solvent employed
-> nature of the mixture
-> medium used for separation
-> temperature
-> Size of the chamber in which operation is carried out.

5. The refractive indices of most of the glass samples encountered during forensic examination range between

  1. 1.40- 1.50
  2. 1.61- 1.63
  3. 1.51- 1.53
  4. 1.55- 1.59

Answer: (3) 1.51- 1.53

Explanation: More accurately, the refractive indices of most glass samples encountered during forensic examination range between 1.508 and 1.524.

6. The refractive index correction value for glass as accuracy and precision is of approximately:

  1. ±1 × l0-4
  2. ±2 × l0-4
  3. ±3 × l0-4
  4. Both (1) and (2)

Answer: Both (1) and (2)

Explanation: Refractive index correction value for each wavelength (Δnλ) is calculated for the glass in question and is then applied to the measurements of the unknown, resulting in an accuracy and precision of approximately ±1 to ±2 × l0−4. [NCBI]

7. Two glass fragments can be compared with the help of

  1. Physical matching
  2. Refractive index
  3. Density gradient tube
  4. All of the above

Answer: (4) All of the above

8. Density comparison by flotation method is used for:

  1. Paint chips
  2. Soil
  3. Glass
  4. Both (2) and (3)

Answer: (3) Glass

Explanation: Soil is analyzed by density gradient where soil particles are spread based on their density with respect to density of liquid at different levels.

9. The following material can be examined by Density Gradient tube method

(i) Soil (ii) Ink (iii) Paint chips (iv) Cement

  1. (i) and (ii) are correct
  2. (i) and (iii) are correct
  3. (ii) and (iv) are correct
  4. (i), (iii) and (iv) are correct

Answer: (4) (i), (iii) and (iv) are correct

10. The refractive index of glass can be determined by:

  1. Free Flotation Method
  2. Becke Line Method
  3. Polarimeter
  4. None of the above

Answer: (2) Becke Line Method

Explanation: The Becke line method is used to determine the relative refractive index of glass materials. And when the Becke line appears at the inside edge of a glass fragment, this means the glass piece has a greater RI than the surrounding liquid.
-> And the Becke line will disappear in liquid with the same RI.

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