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Q31. Which of the following pairs represent correct plutonic – volcanic equivalents?
The correct answer is Granodiorite – dacite, Nepheline syenite – phonolite. Magma creates different rocks depending on where it cools. If it cools slowly underground, it is 'plutonic'. If the exact same magma erupts and cools quickly, it is 'volcanic'. Granodiorite (plutonic) has the exact same chemical recipe as dacite (volcanic). Nepheline syenite (plutonic) matches phonolite (volcanic). Norite is chemically similar to basalt but belongs to a slightly different classification family than standard gabbro. Dunite is practically pure olivine and does not chemically equal a komatiite eruption.
Q32. Which of the following statements are correct?
The correct answer is Abutments are the sides of the valley supporting the dam structure, Spillways can control the release of water from the reservoir, Galleries serve as passages through the dam. Abutments are the natural rock walls holding the dam tight. Spillways are crucial safety slides that let extra water overflow so the dam doesn't burst. Galleries are hollow inspection tunnels built inside the concrete. Option C is entirely backwards: the 'toe' is the front edge on the dry, downstream side of the dam, while the wet, upstream edge is called the 'heel'.
Q33. Which of the following statements are CORRECT?
The correct answer is Mytilus represents byssally attached bivalves, Nautilus is the only living cephalopod genus with a coiled external shell, The cidaroids are the only echinoid group still living. Mytilus are common mussels that use strong threads (byssus) to glue themselves to rocks. The Nautilus is uniquely famous for being the last living squid-like creature to possess a hard, coiled outer shell. (Note: According to the official exam key, the statement regarding cidaroids is considered a correct option). Trilobites definitely did shed their shells (moult) to grow, making option D factually incorrect.
Q34. Which of the following stratigraphic units contain coal seams?
The correct answer is Barakar Formation, Lakadong Formation. The Barakar Formation is famously the most important and richest source of commercial coal in all of India. The Lakadong Formation, located in Meghalaya, also contains highly prized, economically important coal beds. The Pachmarhi and Panchet formations are primarily composed of barren sandstones and clay deposits that formed in environments lacking massive ancient swamps, so they do not contain thick coal seams.
Q35. Which of the following structures form in marine environment?
The correct answer is Hummocky cross stratification, Herringbone cross stratification. When studying ancient rock patterns, 'Hummocky cross stratification' is the signature left by violent storm waves churning the sandy ocean floor. 'Herringbone cross stratification' is the signature left by ocean tides flowing in and out near the coast. Both strictly indicate a marine (ocean) setting. Lateral accretion mostly happens in winding river channels (fluvial). Barchanoids are wind-blown sand dunes in dry deserts (aeolian), making them incorrect.
Q36. Choose the CORRECT statement(s) out of the following.
The correct answer is Shoreline shifts landward during transgression. In geology, 'transgression' is a specific term for when global sea levels rise and the ocean physically floods onto the continents. Because the water level goes up, the beach (shoreline) is violently forced to retreat backwards toward the land. A seaward shift (regression) or deep river cutting (incised valley) happens when sea levels dramatically drop, completely opposite to a transgression.
Q37. Following are the statements regarding types of sandstone as per Pettijohn’s classification. Which is/are the CORRECT statement(s) out of the following?
The correct answers are Arkose contains more than 25% feldspar., Litharenite contains more than 25% lithic fragment., Quartz arenite contains more than 95% quartz. In textbook sandstone classification, an 'Arkose' must be incredibly rich in pink feldspar (>25%). A 'Litharenite' must be rich in grey rock fragments (>25%). A 'Quartz arenite' is exceptionally pure, clean beach sand (>95% quartz). However, 'Greywacke' is simply a dirty sandstone with more than 15% mud matrix, not a bizarrely high 90% (which would just be pure mudstone).
Q38. Which of the following statement(s) regarding hydrocarbon occurrence is/are CORRECT?
The correct answers are Gandhar field is in Cambay basin., Digboi field is in Assam basin. In Indian petroleum geology, the Gandhar field is indeed a massive producer located squarely in the Cambay basin. The historic Digboi field is famously located in the Assam basin. Bombay High oil primarily sits in younger Cenozoic (Miocene) limestone, not Mesozoic. Ankleshwar oil sits in Tertiary sandstone reservoirs, not limestone.
Q39. Which among the following statement(s) is/are TRUE?
The correct answers are Attrition is more dominant in aeolian than in glacial environment., Centrifugal force drives the sediment-laden water outward when the river channel meanders., The downstream water velocity in a river channel increases upward from the channel bed towards the water surface. Wind (aeolian) aggressively blasts grains against each other (attrition), while ice just crushes them. Water swings around river bends due to centrifugal physics. River flow is fastest at the top because friction from the rocky bottom slows the deep water down. A U-shaped valley is strictly carved by glaciers, not rivers (fluvial).
Q40. Which mineral(s) among the following represent(s) AB2O4 composition?
The correct answers are Spinel, Magnetite, Chromite. In mineralogy, the chemical formula AB2O4 defines the 'Spinel group' of minerals. True Spinel is MgAl2O4. Magnetite is famously Fe2+Fe3+2O4. Chromite is FeCr2O4. All three perfectly fit the exact atomic ratios of one A atom, two B atoms, and four Oxygen atoms. Ilmenite is an iron-titanium oxide with the formula FeTiO3, making its atomic structure completely different and incorrect.