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Q21. Which of the following combinations of Basin and Formation is/are CORRECT?
The correct answer is Cauvery Basin – Niniyur Formation, Assam Basin – Tipam Formation, Bengal Basin – Jalangi Formation. In Indian geology, specific rock layers (Formations) are tied to geographical regions (Basins). The Niniyur Formation correctly matches the Cauvery Basin, Tipam matches the Assam Basin, and Jalangi matches the Bengal Basin. The Dhok Pathan Formation is part of the Siwalik Group found in the Himalayas, completely unrelated to the coastal Kutch Basin, making option D wrong.
Q22. The attitude of a fault plane was measured to be 350, 75E. The rake of the slickenline on the fault plane was found to be 90. Which of the faults listed below satisfy(ies) these observations?
The correct answer is Dip-slip fault, Normal fault, Reverse fault. A rake of 90 degrees means the scratches on the rock go perfectly straight up and down the slant of the fault. This up-or-down only motion is called 'dip-slip'. Normal and Reverse faults are both specific types of dip-slip faults. Strike-slip faults move horizontally (side-to-side), so their scratches would be at 0 degrees, making it the only wrong option.
Q23. Which of the following optical properties CORRECTLY indentify(ies) the apatite {0001} section?
The correct answer is Isotropic under crossed nicols, Centered uniaxial interference figure. When looking down the {0001} crystal plane of Apatite under a polarizing microscope, the light passes straight through its unique optic axis. Because of this, it stays completely dark even when rotated (appearing 'isotropic'), and it yields a perfectly centered cross shape known as a 'uniaxial interference figure'. Because it stays dark, it cannot show bright second-order colors or high birefringence, making those options wrong.
Q24. Which of the following types of dunes form(s) primarily by uni-directional wind?
The correct answer is Parabolic dunes, Barchan dunes. When wind blows consistently from only one direction (uni-directional), it shapes sand into specific crescent-like forms, namely Barchan dunes and Parabolic dunes. Linear dunes usually form from winds blowing from two slightly different directions. Star dunes form in areas where the wind constantly changes and blows from many different directions, making them incorrect.
Q25. Which of the following is/are used to estimate the strength of a rock mass?
The correct answer is RQD. To figure out how strong and safe an underground rock wall is, geologists use RQD (Rock Quality Designation), which measures how solid or fractured drill cores are. API gravity measures how heavy crude oil is. Resistivity measures how well rock conducts electricity. Kriging is a mathematical tool used in statistics. None of these other three measure physical rock strength, making them incorrect.
Q26. What type(s) of fossil remains is/are studied in ichnology?
The correct answer is Tracks and trails, Burrows and bioturbation. 'Ichnology' is the specific branch of paleontology that studies fossilized behavior, rather than the actual bodies of creatures. Therefore, ichnologists study footprints (tracks and trails) and homes dug into mud (burrows and bioturbation). The physical bones of fishes/amphibians and plant parts like spores/pollens are studied as 'body fossils' by other specialists, not ichnologists, making them incorrect.
Q27. A metamorphosed basaltic assemblage can include the minerals
The correct answer is garnet-omphacite, hornblende-plagioclase, glaucophane-lawsonite. Basalt is a dark lava rock rich in iron and magnesium. When buried and cooked (metamorphosed), its chemistry creates specific mineral pairs: garnet and omphacite under extreme pressure (eclogite); hornblende and plagioclase under moderate heat (amphibolite); and glaucophane and lawsonite under cold, high pressure (blueschist). Staurolite, however, requires a massive amount of aluminum to form, which basalt doesn't have (staurolite forms from muddy shales instead).
Q28. Identify the correct stratigraphic successions ordered from oldest to youngest.
The correct answer is Semri Group - Kaimur Group - Rewa Group - Bhander Group, Papaghni Group - Chitravati Group - Nallamalai Group - Kurnool Group. Geologists divide major Indian rock formations into specific age groups. In the massive Vindhyan basin, the correct timeline is Semri (oldest), then Kaimur, Rewa, and finally Bhander (youngest). In the Cuddapah basin, the correct timeline is Papaghni, Chitravati, Nallamalai, and then Kurnool. Options A and D list these exact same layers but in a scrambled, incorrect chronological order.
Q29. The acceleration due to gravity on the Earth’s surface depends on
The correct answer is latitude, elevation, topography of the surrounding terrain. Gravity is not exactly the same everywhere. Because Earth is slightly squashed, you are closer to the core at the poles than the equator, so 'latitude' changes gravity. The higher you climb a mountain ('elevation'), the weaker gravity gets. Finally, massive dense mountains nearby can exert their own tiny pull ('topography'). Walking east or west along a flat line ('longitude') does not change your distance from Earth's center, so it does not affect gravity.
Q30. Which of the following genera are stem fossils?
The correct answer is Dadoxylon, Vertebraria. In paleobotany, fossils are named based on the plant part found. 'Dadoxylon' is the scientific name given specifically to ancient, petrified tree trunks (stems/wood). 'Vertebraria' is the distinctive root and stem system of the famous ancient Glossopteris plant. Conversely, Dicroidium and Ptilophyllum are both names designated strictly for fossilized leaves and fronds, meaning they are not stem fossils.