| Post Name | Geophysical Assistant - Ground Water |
|---|---|
| Question Paper Code | 027/2026/OL |
| Category Code | 190/2025 |
| Date of Test | 17 February 2026 |
| Exam Type | Online Examination |
| Total Questions | 100 |
1
Most important source of nitrate pollution in groundwater
Answer
C. agricultural fertilizers
2
Darcy's law is applicable when ground water ļ¬ow is
Answer
D. laminar
3
Best example of an aquitard
Answer
D. clay
4
Water hardness is mainly occurred due to presence of
Answer
B. Ca and Mg
5
Aquifer that underlain and overlain by aquiclude is
Answer
C. conļ¬ned aquifer
6
In an unconļ¬ned aquifer the storage coeļ¬cient is approximately equal to :
Answer
C. speciļ¬c yield
7
In Kerala, ļ¬uoride contamination is reported mainly from parts of :
Answer
B. Palakkad and Alappuzha
8
Fluoride contamination in Kerala groundwater is mainly associated with :
Answer
B. crystalline hard rock aquifers
9
The factor which indicates organic pollution in groundwater
Answer
B. BOD
10
Reynolds number in porous media ļ¬ow is used to :
Answer
B. determine laminar or turbulent ļ¬ow
11
The property of an aquifer from which water can be drained by the force of gravity
Answer
A. speciļ¬c yield
12
Seepage velocity is always :
Answer
C. greater than Darcy velocity
13
Where is the ULVZ found within the earth?
Answer
C. near the core-mantle boundary
14
Consider a satellite orbiting the earth in a circular orbit with radius 'r'. Which of the following statements is true?
Answer
A. The square of the period of the planet's orbit is proportional to the cube of the orbit's radius
15
Which of the following expressions is correct for the Bouguer anomaly ? Where , and represent free air anomaly, Bouguer correction and terrain correction, respectively
Answer
A. :
16
The discontinuity located at a depth of 410 km is associated with
Answer
A. Olivine changes to Wadsleyite
17
Which of the following options is correct about the core of the earth?
Answer
C. The outer core geotherm must be above the solidus
18
What makes hotspots reliable indicators of past plate motion?
Answer
B. Hotspots are relatively stationary, whereas plates move
19
Let's assume that the tectonic plate moves with a half-spreading rate of 5 mm/year. The ratio of the sea-ļ¬oor depth away from the spreading centre at a distance of 400 km to 100 km is :
Answer
B. 2
20
Most deep focus earthquakes occur along which type of plate boundary?
Answer
B. convergent boundary
21
The relationship between inclination (I) and latitude (Ī») as per the geocentric axial magnetic dipole model is:
Answer
B. tan I = 2 tan Ī»
22
Which of the following statements is correct?
Answer
C. the core has only 16% of the earth's volume but has almost one-third of the mass
23
Earth's lower mantle is mainly composed of which of the followings?
Answer
D. perovskite and ferropericlase
24
For a tectonic plate having a thickness of 10 km, moving at a rate of 5 mm/year, the thermal diffusivity Īŗ = 10ā»ā¶ mĀ² sā»Ā¹. The thermal Reynolds number (R) is:
Answer
B. 1.58
25
Which of the following is true for the Wadati-Benioļ¬ zone?
Answer
D. a dipping plane of seismicity associated with the subducting lithospheric slab beneath convergent plate boundaries
26
Dimension of viscosity is given by
Answer
A. ML-1T-1
27
What will be the 'geometrical factor' (in m) for Wenner electrode conļ¬guration used in electrical prospecting with current electrode separation as 30 m?
Answer
B. 20
28
The Schlumberger sounding carried out over 1-D resistivity distribution will exhibit which type of resistivity sounding curve?
Answer
A. HA-type
29
The dominant electrical conduction in subsurface rocks happens due which phenomenon?
Answer
B. electrolytic conduction
30
For 2D multi-electrode electrical resistivity imaging survey, a multi-channel resistivity meter will be eļ¬ective in reducing recording time in comparison to a single channel resistivity meter for which electrode conļ¬guration?
Answer
C. Dipole-dipole array
31
Which rock type will exhibit the highest electrical resistivity?
Answer
D. granite
32
In a homogeneous half-space, the depth to the top of a 2D vertical conducting sheet type structure lies at 50m. Now, using Wenner array proļ¬ling, what will be the most appropriate minimum value of inter-electrode spacing to depict this conductor along a horizontal proļ¬le?
Answer
B. 50 m
33
KQ-type Schlumberger resistivity sounding data is recovered in the field. Which type of equivalence will be observed in the interpretation of resistivity (Ļā) and thickness (hā) of the second layer?
Answer
A. hā Ć Ļā = constant
34
For an applied external electric ļ¬eld, the diļ¬erence in the mobility (in the subsurface) of ions in the solution and electrons in the metallic minerals will exhibit which phenomenon in electrical prospecting?
Answer
A. Electrode polarization
35
The resistivity measured in lab for a metallic rock sample at DC and AC (say 10 Hz) current are 50 and 40 m, respectively. What is the % frequency eļ¬ect?
Answer
C. 25%
36
If is steady state voltage and v(t) is transient voltage, then which is the correct relationship to compute chargeability (M) in IP survey?
Answer
B. :
37
How the frequency is aļ¬ected during electromagnetic induction phenomena in the earth?
Answer
C. frequency of secondary ļ¬eld remains the same of the primary ļ¬eld
38
At one skin depth, the amplitude of primary ļ¬eld reduces to what percentage of its amplitude at the earth's surface?
Answer
B. 37%
39
Ionospheric current is the source of primary ļ¬eld in which electromagnetic method?
Answer
B. Magnetotelluric method
40
Which component of ļ¬elds are recorded in magneto telluric method?
Answer
A. Ex, Ey, Hx, Hy, Hz
41
The surface projection of the hypocenter is known as
Answer
A. epicenter
42
Which scale is commonly used to measure the magnitude of an earthquake?
Answer
B. Richter scale
43
The seismic waves are detected and recorded by which instrument
Answer
C. seismometer
44
If P-waves goes from solid to liquid, what would happen to its velocity?
Answer
D. decrease
45
For earthquakes of magnitude 5 and 6, the seismic wave amplitudes are A5 and A6 and the radiated energies are E5 and E6 respectively. Which one of the following is true?
Answer
D. Aā ā 10Aā
and Eā ā 32Eā
46
S-wave does not travel through which layer of the earth?
Answer
C. outer core
47
Which agency is responsible for the preparation of seismic zonation map of India?
Answer
A. Bureau of Indian Standards (BIS)
48
The world-wide standardized seismograph network (WWSSN) is a global network of sesimograph station and built in early :
Answer
C. 1960s
49
What is the term given to the maximum earthquake that is expected to occur once during the design life of the structure?
Answer
B. Design Basis Earthquake (DBE)
50
A focal mechanism solution is determined by
Answer
B. the ļ¬rst motion of P-waves recorded at seismic stations
51
PcP and ScS are reļ¬ected from which boundary in the earth
Answer
B. core mantle boundary
52
Elastic rebound theory explains:
Answer
C. cause of earthquakes
53
Surface waves are generated primarily due to :
Answer
B. interaction of body waves with the earth's free surface
54
When phase velocity decreases monotonically with frequency, the group velocity is :
Answer
C. less than phase velocity
55
Kƶnigsberger ratio refers to
Answer
B. ratio of the intensity of remnant magnetization and induced magnetization
56
Which instrument is called as 'vector magnetometer'?
Answer
A. ļ¬ux-gate magnetometer
57
The Bouguer anomaly obtained after applying all necessary corrections is due to
Answer
C. lateral density variations
58
The liquid used in sensor of a proton procession magnetometer should be rich in
Answer
B. hydrogen
59
Diurnal correction is applied on the geophysical data obtained from one of the geophysical methods
Answer
C. magnetic ļ¬eld data
60
In gravity observation data, terrain correction is
Answer
D. always positive
61
Elevation correction in the gravity data is a combination of
Answer
A. Free-air and Bouguer corrections
62
Which of the geophysical method is based on potential ļ¬eld theory?
Answer
D. Both (1) and (2)
63
Free-air correction is always of opposite sense to
Answer
A. Bouguer correction
64
Free air anomaly is equal to
Answer
A. Observed Gravity Value - Theoretical Gravity Value free-air correction
65
Gravimetry is the science which deals :
Answer
C. gravity method
66
Magnetic susceptibility is a measure of
Answer
C. the ability of a material to become magnetized in an external magnetic ļ¬eld
67
The depth of magnetic source is obtained using
Answer
C. Euler deconvolution
68
International Geomagnetic Reference Field (IGRF) represents :
Answer
A. theoretical magnetic ļ¬eld at any point on the Earth's surface
69
The radioactivity decay law is related to which parameter/parameters?
Answer
D. all of the above
70
What type of radioactive mineral is connected to monazite?
Answer
B. thorium
71
One of the best scintillation detector is made by growing natural crystal of which materials?
Answer
A. sodium iodide
72
What is the name of the line which comes after plot, of the ratio against the ratio ?
Answer
A. isochron
73
Rb-Sr method is well suited for dating earth's history. Why?
Answer
B. long half-life
74
What is the radioactive equilibrium?
Answer
B. number of daughter atoms disintegrating per second is the same as the number being created by disintegration of the parent
75
What is the exact unit of measuring the activity of a radioactive specimen?
Answer
A. Curie
76
Which of the following statements is/are correct about disintegration during reaction? (i) capture of an electron from the innermost shell (ii) beta emission
Answer
C. both (i) and (ii)
77
The reliability of subsurface interpretation is highest when :
Answer
C. geophysical data are correlated with well logs or test-boring data
78
The spontaneous potential (SP) log is mainly useful for :
Answer
A. diļ¬erentiating shale from sandstone formations
79
Spontaneous potential is a measure of the natural electrical potential that develops between :
Answer
C. formation and borehole ļ¬uids
80
Gamma rays recorded in well logging are emitted mainly due to the natural radioactivity of which elements?
Answer
B. potassium, uranium and thorium
81
Which of the following statements regarding weathered zones and gamma ray activity is correct?
Answer
C. weathered zones may show either high or low gamma activity
82
In gamma ray logging, the detector commonly used is a
Answer
C. Scintillation detector
83
Neutron logs are primarily used to estimate :
Answer
C. porosity and water content
84
The sonic log primarily records :
Answer
B. seismic P-wave velocity ( )
85
The waves measured by standard acoustic devices generally travel :
Answer
C. close to the borehole wall
86
The reason for using more than one caliper in a tool is :
Answer
C. non-circular borehole sections
87
In the cement-bond log display, shaded areas represent :
Answer
A. positive wave portions
88
Nuclear Magnetic Resonance (NMR) primarily detects signals from :
Answer
C. hydrogen nuclei
89
The instruments that acquire images in many, narrow, contiguous spectral bands without the visible, near-IR, mid-IR and thermal-IR portions of the spectrum is known as __________
Answer
A. hyperspectral sensors
90
When radiation interact with atmospheric molecules that are much smaller in diameter than the wavelength of the interacting radiation is called __________ scattering.
Answer
B. Rayleigh
91
__________ is the technique for comparing image and reference spectra.
Answer
C. spectral angle mapping
92
Vertical exaggeration (VE) = Where, AVD = Apparent stereoscopic Viewing Distance AB= Air Base, EB = Eye base, H= Height of the camera
Answer
D. (AB/H)(AVD/EB)
93
__________ stores the geometry, topographic information and attribute information of the geographical features.
Answer
A. shape ļ¬le
94
The relationship of electromagnetic spectrum with the associated percent reļ¬ectance is given by ___________
Answer
B. spectral reļ¬ectance curve
95
The azimuth resolution of a SAR can be expressed as
Answer
C. :
96
_________ map shows the bounadries and ownerships of a land.
Answer
D. cadastral
97
The stray pixels are removed prior to use in GIS is known as
Answer
A. despeckling
98
___________ data structure DO NOT provide the precise location information.
Answer
B. raster
99
A greybody has an emissivity that is ________ but is constant at all wavelength.
Answer
C. < 1
100
The advanced very high resolution radiometer is a cross-track multispectral scanner that acquires images with swath width of _________
Answer
D. 2700 km
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