UPSC Static Quiz – Geography : 24 April 2026

Solution: A

• Metamorphic Grade:This refers to the intensity of heat and pressure applied to the parent rock (protolith), usually Shale/Mudstone.
  1. Slate (Low Grade):Shale transforms into Slate. It is fine-grained and splits into flat sheets (slaty cleavage). Minerals are microscopic.
  2. Phyllite (Low-Medium Grade):With more heat/pressure, micas grow slightly larger, giving the rock a satin sheen or glossy look. The surface is often wavy.
  3. Schist (Medium-High Grade):Micas become large enough to be seen with the naked eye (platy texture). The rock is very sparkly (schistosity).
  4. Gneiss (High Grade):Intense segregation occurs. Dark and light minerals separate into distinct bands (Gneissic banding). This is the highest grade before melting occurs (migmatite).

Solution: C

• Chlorofluorocarbons are chemically very stable in the lower atmosphere (troposphere), which allows them to persist long enough to reach the stratosphere. There, high-energy ultraviolet (UV-C) radiation breaks the carbon–chlorine bonds, releasing free chlorine radicals. Hence, statement 1 is correct.
• Statement 2 is correct because halons, which contain bromine, are extremely potent ozone-depleting substances. Bromine radicals are even more efficient than chlorine in destroying ozone, which is why halons were strictly controlled under the Montreal Protocol despite their effectiveness in fire suppression.

Solution: B

• Hygroscopic nuclei are tiny aerosol particles—commonly sea salt, sulfates, and certain organic compounds—that have a strong affinity for water vapor. Their primary role in cloud and fog formation is to act as efficient condensation nuclei.
• Pure water vapor in the atmosphere requires relative humidity close to or exceeding 100% to condense spontaneously, which rarely happens in natural conditions. Hygroscopic particles overcome this limitation because they attract and retain water molecules even at relative humidity slightly below 100%.
• Due to their soluble nature, they dissolve partially in the absorbed water, lowering the vapor pressure around the droplet (Raoult’s effect). This makes condensation thermodynamically favorable.

As a result, water droplets can form more easily and grow in size, leading to the development of cloud droplets or fog. This process is fundamental to cloud microphysics and explains why maritime air masses rich in salt particles readily form clouds and fog compared to cleaner continental air masses.

Solution: D

Bleaching is a generalized stress response, not just a heat response.

1. Solar Irradiance:High UV levels damage the photosynthetic apparatus of zooxanthellae, causing oxidative stress and expulsion. (Trigger).
2. Extreme Low Tides:Aerial exposure leads to desiccation (drying) and rapid heating/cooling. (Trigger).
3. Reduced Temperature:Corals are sensitive to cold. The 2010 Florida cold snap caused massive bleaching when temperatures dropped significantly below the 18°C threshold. (Trigger).
4. Cyanide Fishing:Sodium cyanide is used to stun fish. It is toxic to corals and causes the polyp to expel the algae or die. (Trigger).

Solution: B

• Pair 1 is correctly matched: Sheet erosion is the uniform removal of soil layers, often initiated by the kinetic energy of raindrops (splash) breaking soil aggregates.
• Pair 2 is correctly matched: Salinization occurs when evaporation rates exceed precipitation (common in arid zones), drawing salt-rich groundwater to the surface via capillary action. It is exacerbated by irrigation without drainage.
• Pair 3 is incorrectly matched: Gully Erosion is an advanced form of water erosion where runoff concentrates in channels, cutting deep ditches. The description given (“removal by high-velocity winds”) refers to Wind Erosion (Deflation).