NCERT Exemplar Solutions Class 7 Science Solutions for Forests: Our Lifeline - Exercise in Chapter 17 - Forests: Our Lifeline

Question 1 Forests: Our Lifeline - Exercise

Which of the following serves as green lungs?

(a) The green pigment of the plants

(b) Forests

(c) Kitchen gardens

(d) Greenhouse gases


The answer is (b) Forests


Plants release oxygen during photosynthesis which is used by all the organisms. Plants help to maintain the concentrations of CO2 and Oxygen Hence they are called as green lungs.

Video transcript
"hi everyone my name is shrisher and welcome back to another homework session of lido let's take a look at today's question write t for true and f for false for each of the given statement the difference of to perfect square is a perfect square so what they are saying is that when you uh subtract to perfect square you'll always get a perfect square let's check if that is true or not let's take two perfect squares uh let's find out the perfect square of 3 4 square first which is 16 and then let's find the perfect square of 3 3 square is 9 so let's subtract 16 and 9 16 and 9 will give you 7 7 is not a perfect square right not a perfect square it is not a perfect square now let's take an example of another let's take one more example 5 square is 25 let's now subtract 25 with 9 so 5 square minus 3 square 5 square is 25 and 3 square is 9 equals to 16 this is 4 square right now you are getting a perfect square this time around we are getting a perfect square so what can i conclude from both the example sometimes you will get a perfect square sometimes you will not get a perfect square so it is not necessary to get a perfect square all the time it can be any number that you will get all right that is why the given statement is false because what they are implying is that every time you take the difference of two perfect squares you'll get a perfect square which is not necessarily true so this is false all right so that's it for this question if you have any doubt you can drop a comment and don't forget to like and subscribe to this channel for regular updates thank you i'll see you next time "
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