51. Which method is most suitable for detecting groundwater table? A. Gravity method B. Magnetic survey C. Electrical resistivity D. GPR Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Electrical resistivity can identify changes in moisture content, helping map the groundwater table.
52. Gravity anomaly data can be corrected for terrain effects using: A. Bouguer correction B. Diurnal correction C. Magnetic calibration D. Drift adjustment Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option A Solution: Bouguer correction compensates for variations in elevation and terrain to isolate true subsurface anomalies.
53. Magnetic surveys are ineffective in areas with: A. Iron-rich soil B. Sedimentary basins C. Urban infrastructure D. Clay-rich layers Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Urban infrastructure creates cultural noise in magnetic data due to metal, pipes, and cables.
54. Which seismic method provides better detail near the surface? A. Seismic reflection B. Seismic refraction C. Down-hole logging D. VSP Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option A Solution: Seismic reflection offers higher resolution and is more effective for shallow subsurface mapping.
55. What does the term 'apparent resistivity' refer to? A. True resistivity value B. Average soil density C. Measured resistivity influenced by heterogeneity D. Depth to groundwater Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Apparent resistivity is a field-measured value affected by all layers beneath the electrodes and differs from true resistivity.
56. Electromagnetic (EM) methods are especially sensitive to: A. Density changes B. Electrical conductivity C. Seismic velocity D. Magnetic polarity Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option B Solution: EM methods detect variations in electrical conductivity, useful in mapping water, clay zones, and ore bodies.
57. Which type of waves are used in reflection seismic surveys? A. Refracted waves B. Surface waves C. Reflected body waves D. Rayleigh waves Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Reflection seismic uses reflected body waves to map horizontal and dipping strata.
58. Resistivity decreases with: A. Increased porosity B. Increased clay content C. Lower temperature D. Reduced moisture Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option B Solution: Clay content increases conductivity due to the presence of charged particles and water, reducing resistivity.
59. Which is a non-invasive geophysical method? A. Drilling B. Seismic refraction C. Cone penetration test D. Test pit Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option B Solution: Seismic refraction is a non-invasive method that doesn�t require physical excavation or drilling.
60. Seismic velocity is generally lowest in which of the following materials? A. Basalt B. Granite C. Wet clay D. Limestone Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Wet clay has high moisture and low density, resulting in the slowest seismic velocities among the listed materials.
