1. The approximate speed of sound in air is _______ m/s.   330   1600   3 × 108   5000   Hint Half-n-half Clue   2. Sounds are produced by musical wind-instruments when columns of air are made to vibrate.   True   False   3. Out of the following materials, the best conductor of sound is _______.   Steel   Water   Air   Half-n-half Clue   4. Ultrasonic vibrations are used in medicine for imaging internal organs of the human body.   True   False   5. The number of sound vibrations per second is called _______.   frequency   amplitude   time period   Half-n-half Clue   6. The part of the inner ear shaped like a snail is called the _______.   hammer   cochlea   eardrum   Half-n-half Clue   7. A _______ note is the lowest note obtained on blowing gently across the top of a test-tube.   overtone   fundamental   harmonic   Half-n-half Clue