1. Sounds travels faster in air as compared to water.   True   False   2. The sound of thunder is heard 10 s after the flash of lightning. If the speed of sound in air is 330 m/s, then the cloud is at a distance of _______.   33.0 m   66.0 m   1650 m   3300 m   Hint Half-n-half Clue   3. Ultrasonic vibrations are used in medicine for imaging internal organs of the human body.   True   False   4. The repetition of sound which is reflected from an object is referred to as _______.   the pitch   the amplitude   an echo   Half-n-half Clue   5. Sound can be reflected as well as refracted.   True   False   6. Sounds are produced by musical wind-instruments when columns of air are made to vibrate.   True   False   7. The number of sound vibrations per second is called _______.   amplitude   time period   frequency   Half-n-half Clue