List of top Questions asked in IIT JAM GG

In the following isobaric temperature–composition diagram, the number of common phases in all the invariant points is ________ (Answer in integer). 

A hollow discoid (cylindrical) microfossil has an outer diameter of 20 µm, height 10 µm and wall thickness 1 µm. The internal volume that can be occupied by the organism is ________ µm3. (Use π = 3.14) (Round off to one decimal place.)

The given section with uniform lithology and sedimentation rate records two ash layers dated at 77 Ma and 76 Ma, respectively. An index fossil species present in the lower part of the section becomes extinct at a horizon 7 m above the base. The estimated age of the extinction event is _________ Ma. (Answer in integer.) 

Which mineral(s) among the following represent(s) AB2O4 composition?

On the basis of the following schematic diagram, choose the CORRECT statement(s). 

Match the items in Group I with the corresponding items in Group II. 

Group I                       Group II 
P. Chalcocite                1. Supergene enrichment 
Q. Bauxite                     2. Mechanical accumulation 
R. Monazite placers      3. Magmatic crystallization 
S. Chromite                   4. Residual processes 
 

Match the environment representing physical geological processes in Group I with the corresponding geomorphic landform/feature in Group II.

Group I         Group II
P. Aeolian        1. Drumlin
Q. Glacial         2. Tombolo
R. Fluvial         3. Yardang
S. Coastal         4. Natural levee

Choose the CORRECT pair of crystal systems that represents the optic orientation shown in the figure. (X, Y, Z are the principal optical vibration directions and a, b, c are the crystallographic axes). 

Match the minerals in Group I with the corresponding composition in Group II. 
Group I          Group II 
P. Leucite        1. (K,Na)AlSi3O8 
Q. Andradite   2. NaAlSi2O6 
R. Sanidine      3. KAlSi2O6 
S. Jadeite         4. Ca3Fe2Si3O12 
 

The following diagram represents the prograde sequence of metamorphic zones that develop during Buchan-type of metamorphism (<4 kbar) of typical pelites. Identify the zones labelled P, Q, and R. 

Choose the CORRECT match between items in Group I with the items in Group II. 
Group I                      Group II 
P. Polarity zone           1. Biostratigraphy 
Q. Formation               2. Chronostratigraphy 
R. Biozone                   3. Magnetostratigraphy 
S. Epoch                      4. Lithostratigraphy 
 

Select the answer that is a CORRECT match for the three types of unconformities. (Grey bands = sediments, [ + ] = igneous rock). 

Match the economic deposits (Group I) with their places of occurrence (Group II). 
Group I             Group II 
P. Iron ore         1. Bhatan 
Q. Base metal    2. Sukinda 
R. Chromite       3. Rampura–Agucha 
S. Uranium        4. Bellary 
 

If the indices of refraction of a uniaxial section are \(\epsilon = 1.653\) and \(\omega = 1.544\), and the retardation between the two rays is 550 nm, then the thickness of the section is ________ µm. (Round off to two decimal places.)
A crystal has lattice parameters of \( a = 4.26\, \text{\AA}, \, b = 10.0\, \text{\AA} \) and \( c = 3.44\, \text{\AA} \), respectively. A plane intercepts on the \( a, b, c \) axes at 2.13 Å, 10 Å and 1.72 Å, respectively. The Miller Indices for the plane, written as an integer, is ________. (Answer in integer.)
The weight loss during the conversion of 1 mole of gypsum to anhydrite is ________. (Atomic weights: Ca = 40.0, S = 32.0, O = 16.0, H = 1.0) (Round off to two decimal places.)
A bed with an attitude 020°, 30° NW is rotated 55° counter-clockwise (looking northerly) along its strike line. The dip of the bed after rotation will be _______° NW. (Answer in integer.)
The width of the outcrop of a fault zone on a flat surface is 100 m. A vertical borehole through the fault zone measured its vertical thickness to be 80 m. The true thickness of the fault zone is ________ m. (Round off to two decimal places.)
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In an oblique slip fault with an attitude 000°, 30° E, the net slip vector has a length of 20 m and a rake of 30° S on the fault plane. The displacement of a horizontal bed along the fault trace in a plane perpendicular to the strike of the fault is ________ m. (Answer in integer.)
If the activity of a radioactive mineral falls from 800 counts/s to 500 counts/s in 80 minutes, the half-life of the mineral is ________ minutes. (Round off to two decimal places.)
Choose the CORRECT statement(s) out of the following.
A marine organic-rich, black shale with tiny pyrite crystals shows complete absence of body or trace fossils. Which of the following statement(s) is/are TRUE?
Which among the following statement(s) is/are TRUE?
Which of the following statement(s) regarding hydrocarbon occurrence is/are CORRECT?
Following are the statements regarding types of sandstone as per Pettijohn’s classification. Which is/are the CORRECT statement(s) out of the following?