Chapter 25 · 6 hours
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NEB Class 12 past exam questions
Past questions and answers
5 questions set from this chapter, 1 of them more than once; 1 is most repeated (set, or a close variant set, in 3 or more exams). Most repeated first.
- Most repeated · 3 of 7 exams
- Asked 3 times
- 2082 Baishakh · 1 mark
- CDC model question 2078, Physics · 1 mark
- 2080 Baishakh · 1 mark
- 2082 model · 1 mark
What is the point where the seismic waves start called?
(a) epicentre
(b) hypocentre
(c) metacentre
(d) seismic centre
Answer
(b) hypocentre
The hypocentre (focus) is the point inside the earth where the rocks first break and the seismic waves start. The epicentre is the point on the earth's surface directly above the hypocentre.
Answer checked by Opus 5.5 · Oct 14, 2026
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- 2080 Baishakh · 1 mark
Which of the earthquake waves is first recorded on the seismograph?
- (a) P-waves
- (b) Rayleigh Waves
- (c) S-Waves
- (d) Love Waves
Answer
(a) P-waves
P-waves (primary, longitudinal waves) are the fastest seismic waves (about 6 to 8 km/s in the crust), so they reach the seismograph first, followed by S-waves and then the surface (Love and Rayleigh) waves.
Answer checked by Opus 5.5 · Oct 14, 2026
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- 2083 Baishakh · 2 marks
How do P and S waves differ? [2]
Answer
| P-waves (primary waves) | S-waves (secondary waves) |
|---|---|
| Longitudinal waves: particles vibrate along the direction of wave travel (compressions and rarefactions). | Transverse waves: particles vibrate perpendicular to the direction of wave travel. |
| Fastest seismic waves (about 6 to 8 km/s in the crust), so they arrive first at a seismograph. | Slower (about 3.5 to 4.5 km/s), so they arrive after the P-waves. |
| Can travel through solids, liquids and gases. | Can travel only through solids, not through liquids (so they cannot pass through the earth's liquid outer core). |
| Usually cause less damage. | Have larger amplitude and cause more shaking and damage. |
Answer checked by Opus 5.5 · Oct 14, 2026
Test yourself · 2 MCQs
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- 2080 Baishakh · 1 mark
P-waves are
(a) Longitudinal
(b) Transverse
(c) Electromagnetic
(d) Ultrasonic
Answer
(a) Longitudinal
P-waves (primary waves) are seismic waves in which the particles of the earth vibrate parallel to the direction of propagation. They are longitudinal, travel through solids and liquids, and are the fastest seismic waves.
Answer checked by Claude Sonnet · Oct 21, 2026
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- NEB model question 2079, Physics 1021 · 1 mark
What causes earthquakes?
(A) The flow of magma
(B) The expansion of the earth's crust
(C) The rubbing together of earth's plates
(D) Tsunami
Answer
(C) The rubbing together of earth's plates
Most earthquakes happen when tectonic plates of the earth's crust move past, collide with or slide under one another. Stress builds up at the plate boundaries and is suddenly released as rocks slip along faults, sending out seismic waves.
Answer checked by Opus 5.5 · Oct 14, 2026
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Questions from NEB Class 12 2079 Physics, 1021 'O' (Board exam, Jestha 2079, the set used outside Bagmati (typed copy)), NEB Class 12 2079 Physics, 1021 'V' (Board exam, Jestha 2079, the Bagmati set (typed copy)), NEB Class 12 2080 Physics, 1021 'Q' (Board exam, Baishakh 2080 (scan)), NEB Class 12 2081 Physics, 1021 'C' (Board exam, Baishakh 2081 (scan)), NEB Class 12 2082 Physics, 1021 'H' (Board exam, Baishakh 2082 (scan)), NEB Class 12 2083 Physics, 1021 'E' (Board exam, Baishakh 2083 (scan)), NEB model question 2079, Physics 1021 (NEB's model paper for the 2080 exam), CDC model question 2078, Physics (CDC's model paper, in the Grade 12 specification grid), NEB Class 12 2080 Physics 1021 (nebexam.com 'Old Question 2080', same as its 'Model Question Set B') (Board-style paper typed on nebexam.com as the 2080 old question, 75 marks; not the Q-set already on the site (neb-2080-q)), NEB Class 12 Physics 1021 Model Question 2082 (NEB model paper, 2082 (typed copy on nebexam.com)) and NEB Class 12 Physics Model Question 2079, Set I (NEB model paper, Set I, 2079 (questions typed at the foot of a solutions post; solutions not used)). Answers are written for this site; check them against your class notes.
Chapter titles and hours from the official syllabus ↗