Important Questions for CBSE Class 9 Science Chapter 12 Sound IMPORTANT QUESTIONS 1 MARK QUESTIONS Question.1 What is SONAR? [SAII-2014] Answer. SONAR (Sound Navigation And Ranging) is a technique for determining water depth and locating underwater objects, such as reefs, submarines, and schools of fish. Question.2 Define one hertz. [SAII-2013] Answer. One hertz is … [Read more...]