CSS - PMS - CCE - PCS - General Science
Organs
Which organ is considered the control center of the human body?
A. Heart
B. Brain
C. Liver
D. Kidney
Correct Answer: B
The brain controls and coordinates most body functions through the nervous system.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Ultrasound
Which industrial application uses ultrasound?
A. Increasing gravity
B. Detecting internal flaws in materials
C. Producing sunlight
D. Changing atomic number
Correct Answer: B
Ultrasonic non-destructive testing detects cracks and discontinuities by reflected waves.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Ultrasound
Which animals famously use ultrasonic echolocation?
A. Most plants
B. Earthworms only
C. Elephants only
D. Bats
Correct Answer: D
Many bats emit and detect ultrasonic calls for navigation and hunting.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Ultrasound
How does pulse-echo ultrasound determine distance?
A. By measuring the time taken for echoes to return
B. By counting electrons
C. By using gravity
D. By measuring color only
Correct Answer: A
Distance can be inferred from sound speed and round-trip travel time.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Ultrasound
Which medical technique uses ultrasound to produce images inside the body?
A. Electrocardiography only
B. Endoscopy only
C. Radiography only
D. Ultrasonography
Correct Answer: D
Diagnostic ultrasound forms images from echoes of high-frequency sound waves.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Ultrasound
What approximate frequency marks the upper limit of normal human hearing?
A. 2 MHz
B. 20 kHz
C. 200 Hz
D. 20 Hz
Correct Answer: B
The common textbook range is about 20 Hz to 20 kHz.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Ultrasound
What is ultrasound?
A. Radio waves
B. Sound with frequency above the upper limit of human hearing
C. Visible light
D. Sound below 1 Hz only
Correct Answer: B
Ultrasound typically means frequencies above about 20 kHz.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Sonic Boom
Which environmental factor affects the local speed of sound in air strongly?
A. Magnetic north only
B. Color of the aircraft
C. Time zone
D. Temperature
Correct Answer: D
Sound speed in air increases with temperature.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Sonic Boom
What shape is commonly associated with the shock-wave pattern behind a supersonic object?
A. Perfect sphere only
B. Mach cone
C. Cylinder only
D. Flat plane only
Correct Answer: B
Supersonic disturbances form a conical wavefront.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Sonic Boom
Is a sonic boom a single event created only when an aircraft first crosses Mach 1?
A. No, shock waves persist while supersonic flight continues
B. Only when engines turn off
C. Yes, only at the instant of crossing
D. Only during landing
Correct Answer: A
A supersonic object continuously generates shock waves; an observer hears the boom as they pass.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Sonic Boom
An aircraft flying at Mach 2 is moving at approximately what relative speed?
A. Half the local speed of sound
B. Twice the local speed of sound
C. Twice the speed of light
D. Exactly 2 m/s
Correct Answer: B
Mach 2 means velocity is two times the local sound speed.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Sonic Boom
What does Mach 1 mean?
A. One meter per second
B. Speed equal to the local speed of sound
C. Half the speed of sound
D. Twice the speed of light
Correct Answer: B
Mach number is speed divided by local sound speed.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Sonic Boom
What causes a sonic boom?
A. Shock waves produced by an object moving faster than sound
B. Light reflecting from a mirror
C. Any object moving slowly
D. A quiet engine
Correct Answer: A
Supersonic motion compresses pressure disturbances into shock waves.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Pitch
What aspect distinguishes two instruments playing the same note at the same loudness?
A. Timbre
B. Pitch only
C. Gravity
D. Frequency only
Correct Answer: A
Different harmonic content and waveform shapes create different timbres.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Pitch
Which instrument property changes pitch when string length is changed?
A. Vibration frequency
B. Mass of the listener
C. Temperature of the instrument case only
D. Air color
Correct Answer: A
Shorter or tighter strings generally vibrate at higher frequencies.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Pitch
Does higher amplitude necessarily mean higher pitch?
A. Yes, always
B. No
C. Only in vacuum
D. Only for ultrasound
Correct Answer: B
Amplitude mainly affects loudness, whereas frequency mainly affects pitch.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Pitch
Lower frequency generally produces what perceived pitch?
A. Higher pitch
B. Higher loudness necessarily
C. Lower pitch
D. No sound
Correct Answer: C
Pitch tends to decrease as frequency decreases.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Pitch
Higher frequency generally produces what perceived pitch?
A. Always louder sound
B. No pitch
C. Lower pitch
D. Higher pitch
Correct Answer: D
Pitch tends to increase with frequency.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Pitch
What is pitch?
A. Wave speed only
B. Sound intensity only
C. Perception of how high or low a sound is
D. Sound duration only
Correct Answer: C
Pitch is strongly related to sound frequency.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Frequency
Which property of sound is primarily related to frequency?
A. Timbre only
B. Loudness only
C. Speed only
D. Pitch
Correct Answer: D
Higher frequency is generally perceived as higher pitch.