11th Chemistry - Book Back Answers - Unit 15 - English Medium Guides

 

 

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Tamil Nadu Board 11th Standard Chemistry - Unit 15 : Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 15 – Chemistry from the Tamil Nadu State Board 11th Standard Chemistry textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Chemistry Unit 15 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 11 students! Prepare well and aim for top scores. Thank you!

Unit 15 :Environmental Chemistry

I. Choose the best answer.

1. The gaseous envelope around the earth is known as atmosphere. The egion lying between an altitudes of 11-50 km is __________
a) Troposphere
b) Mesosphere
c) Thermosphere
d) stratosphere
Answer Key:
d) stratosphere
 
2. Which of the following is natural and human disturbance in ecology?
a) Forest fire
b) Floods
c) Acid rain
d) Green house effect
Answer Key:
a) Forest fire
 
3. Bhopal Gas Tragedy is a case of _____________
a) thermal pollution
b)air pollution
c) nuclear pollution
d) land pollution
Answer Key:
b)air pollution
 
4. Haemoglobin of the blood forms carboxy haemoglobin with
a) Carbon dioxide
b) Carbon tetra chloride
c) Carbon monoxide
d) Carbonic acid
Answer Key:
c) Carbon monoxide
 
5. Which sequence for green house gases is based on GWP?
a) CFC > N₂O > CO₂> CH₄
b) CFC > CO₂> N₂O > CH₄
c) CFC > N₂O > CH₄> CO₂
d) CFC > CH₄> N₂O > CO₂
Answer Key:
c) CFC > N₂O > CH₄> CO₂
 
6. Photo chemical smog formed in congested metropolitan cities mainly consists of
a) Ozone, SO₂ and hydrocarbons
b) Ozone, PAN and NO₂
c) PAN, smoke and SO₂
d) Hydrocarbons, SO₂ and CO₂
Answer Key:
b) Ozone, PAN and NO₂
 
7. The pH of normal rain water is
a) 6.5
b) 7.5
c) 5.6
d) 4.6
Answer Key:
c) 5.6
 
8. Ozone depletion will cause
a) forest fires
b) eutrophication
c) bio magnification
d) global warming
Answer Key:
c) bio magnification
 
9. Identify the wrong statement in the following
a) The clean water would have a BOD value of more than 5 ppm
b) Greenhouse effect is also called as Global warming
c) Minute solid particles in air is known as particulate pollutants
d) Biosphere is the protective blanket of gases surrounding the earth
Answer Key:
a) The clean water would have a BOD value of more than 5 ppm
 
10. Living in the atmosphere of CO is dangerous because it
a) Combines with O₂ present inside to form CO₂
b) Reduces organic matter of tissues
c) Combines with haemoglobin and makes it incapable to absorb oxygen
d) Diluted the blood
Answer Key:
c) Combines with haemoglobin and makes it incapable to absorb oxygen
 
11. Release of oxides of nitrogen and hydrocarbons into the atmosphere by motor vehicles is prevented by using __________
a) grit chamber
b) scrubbers
c) trickling filters
d) catalytic convertors
Answer Key:
d) catalytic convertors
 
12. Biochemical oxygen Demand value less than 5 ppm indicates a water sample to be
a) highly polluted
b) poor in dissolved oxygen
c) rich in dissolved oxygen
d) low COD
Answer Key:
c) rich in dissolved oxygen
 
13. Match the List I with List II and select the correct answer using the code given below the lists 

Code
            A         B         C         D
a          3          4          1          2
b          2          1          4          3
c          4          3          2          1
d          2          4          1          3
Answer Key:
c          4          3          2          1
 
14. 

Code:
            A         B         C         D
a          1          2          3          4
b          3          4          2          1
c          2          3          4          1
d          4          2          1          3
Answer Key:
b          3          4          2          1
 
       The questions gives below consists of an assertion the reason. Choose the correct option out of the choices given below each question
i) Both (A) and R are correct and (R) is the correct explanation of (A)
ii) Both (A) and R are correct and (R) is not the correct explanation of (A)
iii) Both (A) and R are not correct
iv) (A) is correct but( R) is not correct.
 
15. Assertion (A): If BOD level of water in a reservoir is more than 5 ppm it is highly polluted
Reason(R) : High biological oxygen demand means high activity of bacteria in water
a) i
b) ii
c) iii
d) iv
Answer Key:
d) iv
 
16. Assertion (A): Excessive use of chlorinated pesticide causes soil and water pollution.
Reason (R) : Such pesticides are non-biodegradable.
a) i
b) ii
c) iii
d) iv
Answer Key:
a) i
 
17. Assertion (A): Oxygen plays a key role in the troposphere
Reason (R): Troposphere is not responsible for all biological activities
a) i
b) ii
c) iii
d) iv
Answer Key:
d) iv

 

II. Short Answer Questions

11th Chemistry

III. Long Answer Questions

11th Chemistry

IV. Exercise

11th Chemistry