Which one of the following statements about primary waves of earthquakes is not correct ?
- A.They are similar to sound waves.
- B.They can travel only through solid materials.
- C.They travel through gaseous, liquid and solid materials.
- D.They move faster and are the first to arrive at the surface.
Correct answer
Explanation
The correct answer is B, They can travel only through solid materials. This statement is false because primary waves pass through solids, liquids and gases alike. Primary or P-waves are longitudinal waves: they push and pull the rock in the same direction in which the wave travels, compressing and stretching the material just as sound waves compress air. Since every state of matter can be compressed, P-waves cross the Earth's liquid outer core, though they slow down and bend there. It is the secondary or S-waves that travel only through solids, and their failure to cross the outer core is the key evidence that it is liquid. Option A is a correct statement, since P-waves are longitudinal like sound waves. Option C is a correct statement for the reason given above. Option D is a correct statement, since P-waves are the fastest seismic waves and reach seismographs first, hence the name primary. Exam tip: P-wave = primary, fastest, longitudinal, all media; S-wave = secondary, transverse, solids only; surface waves are the most destructive.
Practice Questions
View allAlluvial soils vary in nature from sandy loam to clay. They are generally
- A.poor in potash and rich in phosphorus.
- B.poor in both potash and phosphorus.
- C.rich in both potash and phosphorus.
- D.rich in potash and poor in phosphorus.
Show answer
Alluvial soils, laid down by rivers, generally contain plenty of potash but lack phosphorus, and they are also often short of nitrogen and humus.
Read the full explanation →Which one among the following State capitals is closest to the Equator ?
- A.Hyderabad
- B.Bhubaneswar
- C.Panaji
- D.Mumbai
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Panaji, the capital of Goa, lies at about 15.5° N latitude, the lowest of the four cities, so it is the closest to the Equator.
Read the full explanation →Which Greek philosopher coined the term "Geography" in the 3rd century B.C.E. ?
- A.Euclid
- B.Plato
- C.Eratosthenes
- D.Clio
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Eratosthenes of Cyrene first used the word "geographia", from the Greek "geo" (earth) and "graphe" (description), so geography means a description of the Earth.
Read the full explanation →Which one among the following States has the longest extension in north-south direction?
- A.Jharkhand
- B.Telangana
- C.Odisha
- D.Chhattisgarh
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Chhattisgarh is a long, narrow state that stretches from about 17.8° N in Sukma district to about 24.1° N in Balrampur district, a north-south length of roughly 700 km.
Read the full explanation →Identify the type of soil on the basis of given characteristics : 1. They contain a large proportion of sodium, potassium and magnesium, and thus, they are infertile. 2. Their structure ranges from sandy to loamy. 3. They are more widespread in western Gujarat, deltas of the eastern coast and in Sunderban areas of West Bengal.
- A.Peaty soil
- B.Laterite soil
- C.Arid soil
- D.Saline soil
Show answer
All three features listed, excess salts of sodium, potassium and magnesium, a sandy to loamy texture and their spread in western Gujarat, the eastern deltas and the Sundarbans, describe saline soils.
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