Selina Solutions Concise Physics Class 10 Chapter 7 Sound Name the unit used to measure the sound level. Solution: The unit to measure the sound level is decibel. Question: 14. What is the safe limit of sound level in dB for our ears? Solution: The safe limit of sound level in dB for our ears is up to 120 dB. Question: 15. What is meant by noise pollution? Name one source of sound causing noise NCERT Books - Download PDF for CBSE Class 1 to 12 - teachoo There is also NCERT Exemplar for Class 6 to 12, with answer files and sample paper files in 1 PDF. Unit 13 Sound; Unit 14 Chemical Effects of Electric Current; Unit 15 Some Natural Phenomena; Unit 6 Linear Inequalities ; Unit 7 Permutations And Combinations ;