Which one of the following statements is not true for a flute, a musical instrument?

Which of the following is not a musical instrument that produces sound by vibrating a string?

Which one of the following statements is true for sound waves propagating in air?

Which one of the following statements about sound is NOT correct?

Which one of the following statements about the speed of sound waves is not correct?

Which of the following statements is NOT correct regarding the travel of sound waves?