This page features a set of multiple-choice questions testing knowledge on sound wave properties like pitch, loudness, and speed.

I'll work through each question step by step to provide accurate answers.

Question 1: When frequency increases, pitch increases. Frequency and pitch are directly related - higher frequency means higher pitch. Loudness relates to amplitude, not frequency. Speed depends on the medium, not frequency. Wavelength would actually decrease when frequency increases (since speed = frequency × wavelength).
- Answer: B (pitch of the sound)

Question 2: Distance = 640m, Time = 2.0s
Speed = Distance ÷ Time = 640 ÷ 2.0 = 320 m/s
- Answer: B (320m/s)

Question 3: Looking at the two wave diagrams:
- Both waves have the same amplitude (same height from center line), so same loudness
- Sound wave 1 has a longer wavelength (fewer cycles in the same time period) than sound wave 2
- Different wavelengths mean different frequencies, which means different pitches
- Answer: D (The waves have the same loudness but different pitch)

Question 4: The standard range of human hearing is from about 20 Hz to 20,000 Hz (or 20 kHz).
- Answer: B (from 20Hz to 20000Hz)

Question 5: Sound travels faster in water than in air. In air it's about 340 m/s, in water it's approximately 1500 m/s.
- Answer: C (1500m/s)

Question 6: The sound travels down to sea-bed and back up. Total distance = 2 × 1000m = 2000m
Time = 1.3s
Speed = Distance ÷ Time = 2000 ÷ 1.3 ≈ 1538 m/s
- Answer: C (1538m/s)

Question 7: Echoes occur because sound reflects off surfaces. Sound waves are longitudinal waves (particles vibrate parallel to wave direction). The echo is faint due to energy loss during travel and reflection, not due to changes in frequency or wavelength.
- Answer: C (The sound waves returning to the student are longitudinal)

Question 8: Ultrasound is sound with frequency above human hearing (>20,000 Hz). It's produced by rapidly vibrating sources. It's NOT uncomfortable (we can't hear it). Its frequency must be greater than 20 kHz, not 300 kHz. Sound cannot travel in vacuum.
- Answer: A (It is produced by a rapidly vibrating source)

Question 9: Sound waves need a medium to travel (can't travel through vacuum). They CAN travel through solids, liquids, and gases. Sound waves are longitudinal, not transverse. They travel at different speeds in different substances.
- Answer: B (They are able to travel through solids)

Question 10: Amplitude determines loudness (lower amplitude = quieter). Frequency determines pitch (lower frequency = lower pitch). If both decrease, the sound becomes quieter AND has a lower pitch.
- Answer: D (The sound is quieter and has a lower pitch)

Final Answer:
1-B, 2-B, 3-D, 4-B, 5-C, 6-C, 7-C, 8-A, 9-B, 10-D