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Q201. Which one of the following statements is correct for Class 1B (Parallel) folds?
The correct answer is Dip isogons are convergent. In structural geology, Ramsay's 'Class 1B' folds are perfectly parallel layers, meaning the actual physical thickness of the rock layer stays exactly the same everywhere. Because of how the geometry of this bending works, if you draw lines connecting points of equal tilt (dip isogons), those lines will strongly point towards each other (converge) at the inside of the fold. The other options describe folds that squish, thin out, or stay perfectly geometric, which are different classes.
Q202. Choose the correct chronological order from oldest to youngest for the following stratigraphic units P - Chitradurga Group; Q - Sargur Group; R - Ajabgarh Group; S - Udaipur Group
The correct answer is Q, P, S, R. In Indian geology, the Sargur Group (Q) is extremely old (Archean), followed by the slightly younger Chitradurga Group (P). Moving to the Aravalli-Delhi mountains, the Udaipur Group (S) is older than the Ajabgarh Group (R). Therefore, the correct historical timeline from oldest to youngest is Sargur, Chitradurga, Udaipur, and then Ajabgarh. The other options mix up these established regional timelines.
Q203. The correct order of increasing stability of minerals during chemical weathering is
The correct answer is olivine, pyroxene, biotite, quartz. According to Goldich's weathering series, minerals that form at the highest temperatures deep underground (like olivine and pyroxene) are the least stable on the Earth's wet, cool surface and weather away first. Minerals that form at lower temperatures (like quartz) are the most stable and resist weathering. Therefore, the sequence from weakest to strongest is olivine, pyroxene, biotite, and finally quartz. Any other order scrambles this natural stability sequence.
Q204. The most abundant metal (by weight %) in the Earth’s crust is
The correct answer is Al. The Earth's crust is mostly made of oxygen and silicon, but among metals, Aluminum (Al) is the most abundant, making up about 8% of the crust's weight. Iron (Fe), Sodium (Na), and Magnesium (Mg) are also present but in much smaller amounts compared to Aluminum, making them incorrect choices.
Q205. Which one of the following is an upper Gondwana flora?
The correct answer is Ptillophyllum. The ancient Gondwana rocks in India are divided into lower (older) and upper (younger) sections based on plant fossils. 'Ptillophyllum' is a classic fossilized plant that specifically defines the younger, Upper Gondwana rocks. Phyllotheca, Glossopteris, and Schizoneura are all famous, but they are characteristic of the older, Lower Gondwana period, making them incorrect.
Q206. Which one of the following optical properties of minerals is NOT observed under crossed nicols?
The correct answer is Pleochroism. In a polarizing microscope, 'crossed nicols' means two polarizing filters are active, blocking normal light. This setup is used to see properties like extinction (when the mineral goes dark), interference colors, and interference figures. 'Pleochroism', which is the mineral changing color as you rotate it, is observed with only one filter (plane-polarized light), so it is not seen under crossed nicols.