ACME ACADEMY

WEEKLY EVALUATION TEST

Subject: Science
Time Limit: 20 Mins
Max Marks: 20 Marks
Student Name:
Roll Number:
Class / Sec:
Date:

GENERAL INSTRUCTIONS:

  1. All questions are compulsory. Carefully read all instructions before starting.
  2. The question paper contains 20 questions.
  3. There is no negative marking for incorrect answers.
  4. Use of mobile phones, smartwatches, or calculators is strictly prohibited during the exam.
1. Which physical action is the primary cause of sound production in all musical instruments?
[1 Mark]
(A) Heating of the surrounding air
(B) Vibration of objects or air columns
(C) Compression of solid materials
(D) The flow of electric current
2. What is the SI unit of frequency for a sound wave?
[1 Mark]
(A) Metre per second (m/s)
(B) Decibel (dB)
(C) Hertz (Hz)
(D) Second (s)
3. In which of the following media will sound travel the fastest?
[1 Mark]
(A) Dry air at 0°C
(B) Humid air at 25°C
(C) Water
(D) Steel
4. What is the generally accepted audible range of sound frequencies for humans?
[1 Mark]
(A) 20 Hz to 20,000 Hz
(B) 2 Hz to 2,000 Hz
(C) 200 Hz to 200,000 Hz
(D) Below 20 Hz
5. Which characteristic of a sound wave is primarily interpreted by the human ear as 'pitch'?
[1 Mark]
(A) Amplitude
(B) Frequency
(C) Speed
(D) Time period
6. Why can astronauts on a spacewalk not hear each other speak directly, without the use of electronic communication devices?
[1 Mark]
(A) The sound is immediately absorbed by their spacesuits.
(B) Sound is a mechanical wave and cannot propagate through the vacuum of space.
(C) Their vocal cords stop vibrating in zero gravity.
(D) Sound travels too fast in space to be perceived.
7. In a sound wave propagating through air, how do the individual air particles behave?
[1 Mark]
(A) They travel continuously along with the wave from the source to the listener.
(B) They vibrate back and forth parallel to the direction of wave propagation.
(C) They vibrate up and down perpendicular to the direction of wave propagation.
(D) They remain completely stationary while the energy passes through.
8. In the graphical representation of a sound wave, what does the 'crest' represent?
[1 Mark]
(A) The region of lowest pressure and density (rarefaction).
(B) The region of maximum air density and pressure (compression).
(C) The point where the wave comes to a complete stop.
(D) The exact average density of the medium.
9. How are the time period (T) and frequency (ν) of a sound wave mathematically related?
[1 Mark]
(A) v = T^2
(B) v = T / 2
(C) v = 1 / T
(D) v × T = λ
10. A loud sound, such as a drum beat, can make rice grains jump on a stretched membrane from a distance. What does this demonstrate?
[1 Mark]
(A) Sound transfers mass from the source to the membrane.
(B) Sound is a form of energy that transfers through the medium.
(C) The grains are magnetically attracted to the drum.
(D) The air in the room is being permanently displaced.
11. What distinguishes a musical note played on a sitar from the exact same note played on a flute at the same loudness?
[1 Mark]
(A) The fundamental frequency is different.
(B) The speed of the sound waves produced.
(C) The timbre, which depends on the pattern and intensity of overtones.
(D) The amplitude of the sound waves.
12. What is the minimum time gap required between an original sound and its reflection for the human ear to distinguish it as an echo?
[1 Mark]
(A) 1.0 s
(B) 0.5 s
(C) 0.1 s
(D) 0.01 s
13. If a sound wave has a frequency of 50 Hz, what is its time period?
[1 Mark]
(A) 50 s
(B) 0.5 s
(C) 0.05 s
(D) 0.02 s
14. During a thunderstorm, a person sees lightning and hears the thunder 4 seconds later. If the speed of sound in air is approximately 340 m/s, roughly how far away was the lightning strike?
[1 Mark]
(A) 340 m
(B) 680 m
(C) 1360 m
(D) 2720 m
15. A ship's sonar sends out an ultrasonic signal to measure the ocean's depth. If the signal returns after 4 seconds and the speed of sound in seawater is 1500 m/s, what is the depth of the ocean?
[1 Mark]
(A) 1500 m
(B) 3000 m
(C) 6000 m
(D) 12000 m
16. Assertion (A): The speed of sound is higher in humid air than in dry air at the same temperature. Reason (R): The speed of sound depends on the properties of the medium, such as humidity and temperature.
[1 Mark]
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is not the correct explanation of A.
(C) A is true, but R is false.
(D) A is false, but R is true.
17. Which of the following is an application of ultrasound?
[1 Mark]
(A) Communication between submarines using radio waves.
(B) Detecting severe storms at a long distance through the air.
(C) Imaging internal human organs without surgery (ultrasonography).
(D) Transmitting television signals.
18. If the frequency of a tuning fork is changed from 256 Hz to 512 Hz in the same room, what happens to the wavelength of the sound produced?
[1 Mark]
(A) It remains the same.
(B) It doubles.
(C) It becomes half.
(D) It becomes four times longer.
19. Modern auditoriums use sound-absorbing materials on walls and ceilings. What specific acoustic phenomenon are they trying to reduce?
[1 Mark]
(A) Echolocation
(B) Pitch distortion
(C) Reverberation
(D) The Doppler effect
20. Why are bats able to fly in complete darkness without hitting obstacles?
[1 Mark]
(A) They have exceptional infrared night vision.
(B) They emit short bursts of ultrasonic waves and analyse the returning echoes to locate objects.
(C) They emit infrasonic waves that push obstacles out of the way.
(D) They follow the Earth's magnetic field lines exclusively.
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