This website is made to help students prepare for their competitive exams with ease and confidence.
Q1. A mineral displays magenta interference colour (retardation, Dm = 550 nm) under crossed polarized light. If an accessory plate adds retardation of 100 nm, the interference colour observed is
Geologists use special microscopes with polarized light that create colorful bands called 'interference colors', measured in nanometers. 550 nm is magenta, which is the end of the 1st order colors. Adding a 100 nm plate shifts the total to 650 nm, which falls perfectly into the '2nd order blue' color range.
Q2. According to Dunham’s classification, which one of the following limestones is grain-supported and contains mud?
Dunham's classification names limestones based on their texture. 'Mud' means microscopic fine particles. If a rock is mostly made of larger grains touching each other (grain-supported) but still has some mud filling the tiny spaces between them, it is called a 'Packstone'.
Q3. The density contrast across which one of the following transitions in the Earth is maximum?
The Earth is made of layers: a rocky crust, a rocky mantle, and a dense metallic core. The biggest jump in weight (density) occurs when moving from the heavy rocks of the lower mantle into the liquid iron of the outer core.
Q4. The longitude of the person’s position at a place 3 hours ahead of UTC (Prime Meridian) is
The Earth rotates 360 degrees in 24 hours, meaning it spins 15 degrees every hour. If a location's time is 3 hours ahead of the Prime Meridian (0 degrees), it must be further east. 3 hours * 15 degrees = 45 degrees East.
Q5. Which one of the following characteristic mineral assemblages represents eclogite facies metamorphism of a pelitic protolith?
'Facies' refers to the temperature and pressure conditions a rock experienced. Eclogite facies means extremely high pressure deep in the Earth. Under these intense conditions, a clay-rich rock turns into very dense minerals like talc, kyanite, phengite, and garnet.
Q6. Which one of the following CORRECTLY describes the footwall block relative to the hanging wall of a planar normal fault?
Imagine a slanted crack in the ground where rocks slide, known as a fault. The block resting on top of the slant is the 'hanging wall', and the block underneath is the 'footwall'. In a 'normal fault', gravity pulls the hanging wall down. This means the footwall is located below the fault plane and relatively moves up compared to the falling hanging wall.
Q7. Which one of the following does NOT have a polymorph?
A 'polymorph' is when the exact same chemical ingredients can form different crystal shapes, like carbon making both graphite and diamond. Calcite, Pyrite, and Diamond all have polymorphs. Fluorite only ever forms one crystal shape, so it has no polymorphs.
Q8. Which one of the following drainage patterns is formed by stream paths that follow circular segments?
Drainage patterns are the shapes rivers make over the landscape. 'Annular' means ring-shaped. This happens when rivers flow around a circular dome of rock, following the curved, softer rock layers in a circle.
Q9. Which one of the following elements in the Earth is a chalcophile and shows siderophilic behavior?
Elements like to bond with different things in nature. 'Chalcophile' means it loves sulfur. 'Siderophile' means it loves iron and sinks to the Earth's core. Iron (Fe) strongly bonds with sulfur (forming the mineral pyrite) and is also the main ingredient of the Earth's core.
Q10. Which one of the following is a fluorite deposit?
Dongargaon in Maharashtra is a well-known geological deposit where the mineral fluorite (calcium fluoride) is abundantly found and mined.