List of top Questions asked in IIT JAM GG

Two sandstone reservoir rocks R1 and R2 have 25 % porosity each but the permeability of R1 is higher than that of R2. Which of the following can explain this difference in permeability?

Sphalerite shows limited isomorphism. Consider a colorless sphalerite having 33% S and 67% Zn. Then, in a black-coloured sphalerite, with a 15% Fe substitution, the ratio of atomic proportions of Zn to that of Fe is ...........

A clinopyroxene crystal in a basalt, measured to have a composition of \( \text{Mg}_{1.2} \text{Fe}_{0.4} \text{Ca}_{0.4} \text{Si}_2 \text{O}_6 \), will have an Mg-number (Mg) of............%. (In integer)

A sandstone sample with 100 % quartz has a porosity of 30 %. The sample is dry and the density of quartz is 2.65 g/cc. The bulk density of the sandstone sample is ............ g/cc. (Round off to one decimal place)

In a mineralized staurolite-garnet-biotite schist, the estimated metasomatic sulfide mineralization is 4%, with ore mineral proportions of 30% chalcopyrite, 20% pyrite, and the rest being magnetite. The maximum grade of Cu will be   _ __ _ g/ton (Round off to the nearest integer)

Based on the figure, the anorthite content of first formed plagioclase crystals from a liquid composition having 50 mole % anorthite is ......... mole % (In integer). 
 


Correct Answer: 74 mole \% 
Solution:

The figure shows variation in optical properties of plagioclase feldspars with composition. A feldspar from a lunar anorthosite, with anorthite mole % of 85, will have a birefringence of ........ (Round off to three decimal places) 
 

Four vertical boreholes are drilled on a flat topography at 50 m intervals along the east-west direction. The boreholes intersect a coal seam at depths of 100 m, 130 m, 160 m and 190 m. The true dip of the coal seam, in degree, is ...............(Round off to two decimal places)
In the isometric system, the difference in the number of symmetry planes in class $4_3m(Hexahedral) class and 2/m3$ (Diploidal) is .......... (In integer)
Consider a perfect Geocentric Axial Dipole model for the geomagnetic field. At a latitude of 30°N, the inclination of a freely suspended magnetic needle, in degree, is ............ (Round off to the nearest integer)
The figure shows the \(^{14}C\) activity with depth in a sediment core from a lake, where the sedimentation rate was uniform. The maximum \(^{14}C\) activity, marking the signature of bomb carbon, was measured at a depth of 45 cm. The rate of sedimentation is ............... mm/year (In integer).

Correct Answer: 0.53
Solution:
A mountain of height 5 km is in static equilibrium with a crustal block of zero elevation. If the density of the crust and the mantle are 2700 and 3300 kg/m\(^3\), respectively, the thickness of the mountain root (h) is ........... km. (Round off to one decimal place)
A metallic mineral weighs 44 g and displaces 11 mL of water when fully immersed. The density of the mineral is ......... g/cc. (In integer)
\ε\(_{Nd}\) is the deviation of \(^{143}\)Nd/\(^{144}\)Nd of a sample relative to CHUR in parts per 10\(^4\). For a pyroxenite with measured \(^{143}\)Nd/\(^{144}\)Nd = 0.512838 and \(^{147}\)Sm/\(^{144}\)Nd = 0.21, the initial \ε\(_{Nd}\) at 1 Ga is ............ (Round off only the final answer to one decimal place)
The figure shows a coral reef deposit at the continental margin since 120 Ma. Assuming that there was no sea-level change, the average subsidence rate of this continental margin is ......... mm/year. (Round off to three decimal places)
The surface subsidence at a horizontal distance \( X \) from the centerline of a cylindrical tunnel is given by \( S = S_{\text{max}} \times \exp\left(\frac{-X^2}{0.5H^2}\right) \), where \( S_{\text{max}} \) is the maximum subsidence above the tunnel and \( H = 50 \) m is the depth of the tunnel centerline. The ratio of surface subsidence at \( X = 10 \) m to that at \( X = 20 \) m is .............
The true dip of a normal limb associated with asymmetric folding is 20° and the angle that this limb makes with the axial planar cleavage is 35°. The true dip of the axial planar cleavage, in degree, is.........
A hypothetical mineral has the formula \( X_7Si_8O_{22}(OH)_2 \), where X is a cation. The valence state of \( X \) is .............. (In integer)
The lithostatic pressure at the base of a 35 km thick continental crust of average density of 2.8 g/cc is................ \(\times 10^8\) Pa.
An aquifer with a hydraulic conductivity of 60 m/day experiences a head loss of 20 m over a length of 1000 m. The flow of water per unit area, in millimeter per minute, is..............
Which of the following factors affect(s) the intrinsic spatial resolution of remote sensing imagery?
Intrusion of a 10-meter thick dolerite dyke into a boron-rich quartz-garnet-biotite-muscovite-chlorite schist developed a visible symmetric baked zone. Which of the following minerals can develop in this baked zone, 2 meters away from the margin of the dyke?
Which of the following ore types form(s) by magmatic differentiation?
In the following illustration, PQRS is an exposed axial planar cleavage, striking north-south and dipping 40° east. B1 and B2 are the traces of two folded bedding planes on this axial planar cleavage. The fold can be classified as
One mole of a parent nuclide is undergoing radioactive decay. The fraction of atoms of this nuclide that has decayed after three half-lives is.................