Sources of information

Q: Density inside Earth can be inferred from what?

Wave speed and gravity values Wave speed and gravity are both linked with density of materials. Exam tip: treat both as indirect clues.

Q: Information obtained from mining is mostly limited to which part of Earth?

Upper crust Mining gives direct information about only the shallow parts of Earth. Mines are made to obtain useful materials such as coal, metals, and ores, but people cannot safely dig through thousands of kilometres of rock. Therefore, mining is an important direct source of information, yet its reach is very limited compared with the size of Earth. The correct choice is the upper crust, where most mining activity takes place. The inner core, outer core, and lower mantle lie far below the depth reached by mines. Information about these regions must come mainly from indirect evidence, especially seismic waves, gravity observations, and the study of Earth’s magnetic field. Thus option C follows because mining can reveal rocks and conditions near the surface, not the deep interior.

Q: Volcanic lava is not always a direct sample of which deep part of Earth?

Deep core Lava comes from inside but it is not a direct sample of the core. Exam tip: understand the limit of direct sources.

Q: Why are artificial explosions used in studying Earth's interior?

To create artificial waves Artificial explosions create waves used to study rocks below. Exam tip: consider it a controlled indirect method.

Q: Which property of seismic waves helps estimate thickness of Earth's layers?

Travel time Travel time of waves helps infer distance and layers. Exam tip: connect travel time with thickness.

Q: Which source gives clues about magnetic properties of internal materials?

Geomagnetic survey A geomagnetic survey studies variations in Earth’s magnetic field. Such variations provide clues about magnetic and iron-rich materials inside Earth, especially materials associated with the core. Seismic waves are more useful for finding the physical state and density of internal layers, not their magnetic properties. Exam tip: for questions on magnetic properties, link the evidence to geomagnetism.

Q: Internal temperature of Earth can be directly measured by what?

From boreholes or drill holes Temperature can be measured with depth in boreholes. Exam tip: remember it as direct but limited source.

Q: What is the graph obtained from a seismograph called?

Seismogram The direct answer is C, seismogram. A seismograph is the instrument that detects and records ground vibrations caused by earthquakes. The written or drawn record produced by that instrument is called a seismogram. This instrument-record distinction is the main idea. Option A, map, is a representation of places or features on Earth and does not specifically record seismic waves. Option B, bar graph, compares quantities using bars; it is a general graph, not the special earthquake record. Option C is correct because a seismogram shows the movement of the ground or the arrival and strength of seismic waves over time. Option D, hydrograph, normally shows changes in water flow or river discharge, so it is unrelated to earthquake recording. Therefore, do not confuse the device with its output: seismograph is the machine, while seismogram is the record. Memory cue: the instrument ends in “-graph” and its earthquake record is a “seismogram.”

Q: If S waves are absent in a region what can scientists infer?

Liquid material may be present there S waves do not travel in liquids so their absence indicates liquid. Exam tip: this feature of S waves is very important.

01Density inside Earth can be inferred from what?

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Answer and explanation

Correct answer: A. Wave speed and gravity values

Wave speed and gravity are both linked with density of materials. Exam tip: treat both as indirect clues.

Practice questions

01Density inside Earth can be inferred from what?पृथ्वी के अंदर की जानकारी में घनत्व का अनुमान किससे लगाया जा सकता है?

02Why are meteorites linked with the study of Earth's interior?उल्कापिंडों को पृथ्वी के आंतरिक अध्ययन में क्यों जोड़ा जाता है?

03Information obtained from mining is mostly limited to which part of Earth?खनन से मिली जानकारी पृथ्वी के किस हिस्से तक अधिक सीमित रहती है?

04Volcanic lava is not always a direct sample of which deep part of Earth?ज्वालामुखी लावा हमेशा पृथ्वी के किस गहरे भाग का सीधा नमूना नहीं होता?

05Why are artificial explosions used in studying Earth's interior?पृथ्वी के आंतरिक भाग के अध्ययन में कृत्रिम विस्फोट किसलिए किए जाते हैं?

06Which property of seismic waves helps estimate thickness of Earth's layers?भूकंपीय तरंगों का कौन सा गुण पृथ्वी की परतों की मोटाई का अनुमान देने में सहायक है?

07Which source gives clues about magnetic properties of internal materials?किस स्रोत से पृथ्वी के आंतरिक पदार्थों की चुंबकीय विशेषता का संकेत मिलता है?

08Internal temperature of Earth can be directly measured by what?पृथ्वी के अंदर का ताप सीधे किससे मापा जा सकता है?

09What is the graph obtained from a seismograph called?भूकंपलेखी से प्राप्त रेखाचित्र को क्या कहा जाता है?

10If S waves are absent in a region what can scientists infer?यदि एस तरंगें किसी भाग में अनुपस्थित हों तो वैज्ञानिक क्या अनुमान लगा सकते हैं?

11What generally happens when seismic waves pass through rigid material?भूकंपीय तरंगें जब कठोर पदार्थ से गुजरती हैं तो सामान्यतः क्या होता है?

12Why is direct digging to Earth's centre not possible?पृथ्वी के केंद्र तक सीधे खुदाई क्यों संभव नहीं है?

13Which of the following is a direct method of studying Earth's interior?निम्न में से कौन सा आंतरिक भाग के अध्ययन की प्रत्यक्ष विधि है?

14Information obtained from earthquake waves is of what type?भूकंप तरंगों से प्राप्त जानकारी किस प्रकार की होती है?

15What gives a clue that the core is metallic?क्रोड के धात्विक होने का संकेत किससे मिलता है?

16Different layers inside Earth are mainly known through what?पृथ्वी के अंदर की अलग अलग परतों का पता मुख्य रूप से किससे चलता है?

17Which example is the correct match of source and information?कौन सा उदाहरण स्रोत और सूचना का सही मिलान है?

18Which question is most important for knowing the state of internal layers?अंदरूनी परतों की अवस्था जानने के लिए किस प्रश्न का उत्तर सबसे महत्वपूर्ण है?

19Rocks of the ocean floor provide information about what?समुद्री तल की चट्टानों से किसकी जानकारी मिलती है?

20Which evidence is most useful in understanding the boundary between crust and mantle?भू-पर्पटी और मैंटल की सीमा समझने में कौन सा प्रमाण सबसे अधिक उपयोगी है?

21In which method does real material from inside Earth come out for study?किस विधि में पृथ्वी के अंदर से वास्तविक पदार्थ बाहर आकर अध्ययन योग्य बनता है?

22Why are indirect sources needed?अप्रत्यक्ष स्रोतों की आवश्यकता क्यों पड़ती है?

23Which of the following shows a limitation of direct sources?निम्न में से कौन सा प्रत्यक्ष स्रोत की सीमा बताता है?

24Which source helps understand Earth's internal structure without digging?कौन सा स्रोत पृथ्वी के अंदर की संरचना को बिना खुदाई समझने में मदद करता है?

25How are correct conclusions made in the study of Earth's interior?पृथ्वी के आंतरिक भाग के अध्ययन में सही निष्कर्ष कैसे बनाए जाते हैं?

Analytics choices

01Density inside Earth can be inferred from what?

02Why are meteorites linked with the study of Earth's interior?

03Information obtained from mining is mostly limited to which part of Earth?

04Volcanic lava is not always a direct sample of which deep part of Earth?

05Why are artificial explosions used in studying Earth's interior?

06Which property of seismic waves helps estimate thickness of Earth's layers?

07Which source gives clues about magnetic properties of internal materials?

08Internal temperature of Earth can be directly measured by what?

09What is the graph obtained from a seismograph called?

10If S waves are absent in a region what can scientists infer?

11What generally happens when seismic waves pass through rigid material?

12Why is direct digging to Earth's centre not possible?

13Which of the following is a direct method of studying Earth's interior?

14Information obtained from earthquake waves is of what type?

15What gives a clue that the core is metallic?

16Different layers inside Earth are mainly known through what?

17Which example is the correct match of source and information?

18Which question is most important for knowing the state of internal layers?

19Rocks of the ocean floor provide information about what?

20Which evidence is most useful in understanding the boundary between crust and mantle?

21In which method does real material from inside Earth come out for study?

22Why are indirect sources needed?

23Which of the following shows a limitation of direct sources?

24Which source helps understand Earth's internal structure without digging?

25How are correct conclusions made in the study of Earth's interior?