Earth Science

Step 1: Understanding the question.
The question asks for the estimated pressure and temperature at the center of the Earth. This information is critical in understanding the conditions that exist deep within the planet.
Step 2: Analyzing the options.
(A) 360 GPa, 2600 K: Incorrect — The temperature at the Earth's core is estimated to be higher than 2600 K.
(B) 450 GPa, 6000 K: Incorrect — The pressure at the Earth's center is closer to 360 GPa, not 450 GPa.
(C) 360 GPa, 6000 K: Correct — The pressure is around 360 GPa and the temperature at the Earth's core is estimated to be around 6000 K.
(D) 450 GPa, 2600 K: Incorrect — The pressure is too high, and the temperature is too low for the Earth's center.
Step 3: Conclusion.
The correct answer is (C) 360 GPa, 6000 K, as these are the commonly accepted estimates for the Earth's core conditions.

Step 1: Understanding the question.
Nepheline syenite is an intrusive igneous rock that contains a significant amount of nepheline, a feldspathoid mineral. The volcanic equivalent of nepheline syenite is phonolite. Phonolite is an alkaline volcanic rock that shares similar mineralogical features with nepheline syenite.
Step 2: Analyzing the options.
(A) rhyolite: Rhyolite is an acidic volcanic rock with high silica content, not the equivalent of nepheline syenite.
(B) basanite: Basanite is an alkaline volcanic rock, but it does not share the same mineral composition as nepheline syenite.
(C) phonolite: Correct — Phonolite is the volcanic equivalent of nepheline syenite, characterized by similar mineral compositions.
(D) andesite: Andesite is a volcanic rock with intermediate silica content, but not the equivalent of nepheline syenite.
Step 3: Conclusion.
The correct answer is (C) phonolite, as it is the volcanic equivalent of nepheline syenite.

Step 1: Understanding the question.
Conservative plate boundaries are characterized by plates sliding past each other without creating or destroying crust. The most common structure at these boundaries is a transform fault.
Step 2: Analyzing the options.
(A) normal fault: A normal fault occurs where the crust is being pulled apart, which is not typical of conservative boundaries.
(B) growth fault: Growth faults are related to the development of sedimentary basins, not directly associated with plate boundaries.
(C) transform fault: Correct — Transform faults occur at conservative plate boundaries, where plates slide horizontally past each other.
(D) reverse fault: Reverse faults are associated with compressional boundaries, not conservative ones.
Step 3: Conclusion.
The correct answer is (C) transform fault, as transform faults are the primary feature of conservative plate boundaries.

Step 1: Understanding the question.
This question asks to match the earth's layers with their approximate thicknesses. The lithosphere, mantle, core, and other layers vary in thickness.
Step 2: Analyzing the options.
(A) P-3 Q-4 R-1 S-2: Incorrect — The thicknesses are mismatched in this option.
(B) P-4 Q-1 R-3 S-2: Incorrect — The lithosphere and mantle thicknesses are swapped.
(C) P-1 Q-2 R-3 S-4: Correct — The lithosphere has a thickness of about 100 km, the mantle is about 2900 km, the outer core is around 2250 km, and the inner core is about 1200 km.
(D) P-4 Q-3 R-2 S-1: Incorrect — The mantle and outer core are mismatched in this option.
Step 3: Conclusion.
The correct answer is (C) P-1 Q-2 R-3 S-4, as it correctly matches the earth layers with their approximate thicknesses.

Step 1: Understanding the question.
This question asks to match the earth's layers with their approximate thicknesses. The lithosphere, mantle, core, and other layers vary in thickness.
Step 2: Analyzing the options.
(A) P-3 Q-4 R-1 S-2: Correct — The lithosphere has a thickness of about 100 km, the mantle is about 2900 km, the outer core is around 2250 km, and the inner core is about 1200 km.
(B) P-4 Q-1 R-3 S-2: Incorrect — The lithosphere and mantle thicknesses are swapped.
(C) P-1 Q-2 R-3 S-4: Incorrect — The thicknesses are mismatched in this option.
(D) P-4 Q-3 R-2 S-1: Incorrect — The mantle and outer core are mismatched in this option.
Step 3: Conclusion.
The correct answer is (A) P-3 Q-4 R-1 S-2, as it correctly matches the earth layers with their approximate thicknesses.

Step 1: Understanding the ore body and its volume.
The ore body is a cylinder, and the formula for the volume of a cylinder is given by: Where:
- is the radius of the cylinder,
- is the height (or length) of the cylinder.
The diameter of the cylinder is 20 m, so the radius , and the length . Substituting these values into the volume formula: Step 2: Calculating the mass of the ore.
The density of the ore is given as 3500 kg/m , and the metal content is 5%. Therefore, the total mass of the ore is: The metal content in the ore is 5%, so the mass of metal in the ore is: Step 3: Converting the mass into tons and the reserve.
1 ton = 1000 kg, so the mass in tons is: The reserve in million tons is: Step 4: Conclusion.
The reserve of the ore body is 0.21 million tons.

Step 1: Understanding the question.
The question asks for the estimated pressure and temperature at the center of the Earth. This information is critical in understanding the conditions that exist deep within the planet.
Step 2: Analyzing the options.
(A) 360 GPa, 2600 K: Incorrect — The temperature at the Earth's core is estimated to be higher than 2600 K.
(B) 450 GPa, 6000 K: Incorrect — The pressure at the Earth's center is closer to 360 GPa, not 450 GPa.
(C) 360 GPa, 6000 K: Correct — The pressure is around 360 GPa and the temperature at the Earth's core is estimated to be around 6000 K.
(D) 450 GPa, 2600 K: Incorrect — The pressure is too high, and the temperature is too low for the Earth's center.
Step 3: Conclusion.
The correct answer is (C) 360 GPa, 6000 K, as these are the commonly accepted estimates for the Earth's core conditions.

Step 1: Understanding the composition of Earth's crust.
The Earth's continental crust is primarily composed of oxygen (about 46% by weight), followed by silicon (about 28%). These two elements combine to form the most common minerals in the crust, such as feldspar and quartz.

Step 2: Analyzing the options.
(A) silicon: Silicon is abundant in the Earth's crust but is less abundant than oxygen.
(B) aluminium: Aluminium is present in the crust but is less abundant than silicon and oxygen.
(C) oxygen: Correct — Oxygen is the most abundant element in the Earth's continental crust.
(D) iron: Iron is more abundant in the Earth's core, not the continental crust.

Step 3: Conclusion.
The correct answer is (C) oxygen, as it is the most abundant element in the Earth's continental crust.

Step 1: Understanding Earth's shape.
The Earth is not a perfect sphere; it is an oblate spheroid, flattened at the poles and bulging at the equator.
Step 2: Reasoning.
Due to Earth's rotation, the equatorial regions experience a greater outward centrifugal force, increasing the equatorial radius.
Step 3: Conclusion.
Thus, the Earth's radius is maximum at the equator (0° latitude).