This website is made to help students prepare for their competitive exams with ease and confidence.
Q11. The density of a quartz-magnetite rock with 30% magnetite is around:
Using the volume percentage formula: Density = (0.7 * 2.65) + (0.3 * 5.18) ≈ 1.85 + 1.55 = 3.4 g/cc. The closest option is 3.3 g/cc.
Q12. The resistance measured across the faces of the smallest area of cross-section of a 5 cm x 5 cm x 10 cm block of material is 8 Ohms. The resistance measured across the faces of the largest area of cross-section of the same block is:
Using R = ρL/A: Case 1 (Smallest Area 25cm2, L=10cm) gives ρ=20. Case 2 (Largest Area 50cm2, L=5cm) gives R = 20(5)/50 = 2 Ohms.
Q13. Enhanced weathering of the crust due to tectonic uplift reduces atmospheric CO2 and induces cooling on account of:
Uplift exposes fresh silicate rocks. The chemical weathering of silicates draws CO2 from the atmosphere (Urey reaction), leading to global cooling.
Q14. What is the major difference between dissolved N2 & O2 in the surface ocean and dissolved CO2?
Unlike diatomic N2 and O2, CO2 chemically reacts with water upon dissolution to form a series of species: carbonic acid, bicarbonate ions, and carbonate ions (speciation).
Q15. Tsunamis are most likely to be generated when Richter scale magnitudes of earthquakes are:
Tsunamis require massive vertical displacement of the seafloor to move the water column above it, which typically only occurs with very large magnitude (>8) submarine earthquakes.
Q16. One of the following statements is FALSE: 1. Equatorial oceanic Kelvin waves travel eastward at 3 m/s. 2. Equatorial oceanic Kelvin waves travel at 20 m/s eastward. 3. The wavelength of tsunamis is less than the depth of the ocean. 4. Change of Coriolis force facilitates atmospheric Rossby waves
Tsunamis are shallow-water waves. Their wavelengths (often >100 km) are much greater than the average depth of the ocean (~4 km), making statement 3 false.
Q17. In an area of 100 ha, the water table dropped by 5 m due to continuous ground water pumping. If the porosity of the aquifer is 25% and the specific retention is 10%, then the specific yield of the aquifer is:
Total Porosity is the sum of Specific Yield (water that drains by gravity) and Specific Retention (water held by capillary forces). Porosity (25%) = Yield + Retention (10%). Therefore, Specific Yield = 15%.
Q18. Assuming the Earth's magnetic field to be purely dipolar, the ratio of total magnetic field intensity at 45° magnetic latitude to that at the equator will be:
Total field intensity equation: F = F_eq * sqrt(1 + 3*sin^2(Lat)). At 45 degrees, sin(45) = 1/sqrt(2), so sin^2(45) = 1/2. F = F_eq * sqrt(1 + 1.5) = F_eq * sqrt(2.5) = F_eq * sqrt(5/2).
Q19. The most important paleontological evidence for the existence of Gondwanaland is the occurrence of:
The widespread discovery of fossilized Glossopteris leaves across South America, Africa, India, Antarctica, and Australia provides irrefutable evidence that these landmasses were once joined as Gondwanaland.
Q20. Walker circulation is manifested by:
The Walker circulation is driven by the East-West sea surface temperature gradient (non-uniform heating) across the equatorial Pacific Ocean.