# NCERT Exemplar Solutions Class 7 Science Solutions for Wastewater Story - Exercise in Chapter 18 - Wastewater Story

Question 32 Wastewater Story - Exercise

Three statements are provided here which define the terms –

(a) sludge

(b) sewage and

(c) wastewater.

Pick out the correct definition for each of these terms.

(a) The settled solids that are removed in wastewater treatment with a scraper.

(b) Water from the kitchen used for washing dishes.

(c) Wastewater released from homes, industries, hospitals and other public buildings.

a) Sludge

b) Waste water

c) Sewage

Video transcript
"hey guys welcome to lido q a video i am vinit your lido tutor bringing you this question on your screen a sound signal of 128 vibrations per second has a wavelength of 2.7 meter calculate the speed with which the wave travels right now what is given to us frequency is the number of five resistance per second therefore frequency here is 128 hertz wavelength that is denoted by lambda is 2.7 meter therefore speed of wave we know is wavelength into frequency that is equal to 128 into 2.7 that is equal to 345.6 meter per second isn't that easy guys if you still have a doubt please leave a comment below do like the video and subscribe to our channel i'll see you in our next video until then bye guys keep learning keep flourishing"
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