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MARKING SCHEME

CLASS XII

SCIENCE SUBJECTS

CENTRAL BOARD OF SECONDARY EDUCATION

DELHI

2012


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CBSE, Delhi-110301

Published by Secretary, C.B.S.E. 'Shiksha Kendra', 2, Community Centre, Preet Vihar, Delhi - 110301.

Laser typesetting and Printed by Akashdeep Printers, Daryaganj, New Delhi - 110002

Manuscript as such highlights the main value points and does not represent a complete ideal answer.

Manuscript may vary from time to time and year to year.

Price : Rs.

November, 2012 : 250 Copies


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PREFACE

CBSE as a pace setting national Board has constantly been striving to design its evaluation

process in a manner that it is used as a powerful means of influencing the quality of teaching and learning

in the classroom situation. Also, it has to be so designed that it provides constant feedback regarding

the effectiveness of the course content, classroom processes and the growth of individual learners

besides the appropriateness of evaluation procedures.

As a move in this direction, CBSE started the practice of publishing the Marking Schemes with

twin objectives in mind-(i) making the system more transparent and at the same time, (ii) ensuring high

degree of reliability in scoring procedure.

Who are the markers of answer scripts? How do they mark the answer scripts? How can it be

ensured that marking is fair, objective and reliable? Questions of these types naturally arise in the minds

of candidates appearing in the public examination. These questions are equally pertinent to the teachers

who are not adequately exposed to the CBSE system of marking.

Answer Scripts marking is a specialised job. It is assigned to teachers-PGTs for Class XII and

TGTs for Class X who are in direct touch with the subject and have a minimum of 3 years experience

of teaching the subject at that level. Appointment of examiners is made in accordance with the well-

defined norms. Markers examine scripts with the help of detailed guidelines called the 'Marking Schemes'.

It is this tool (Marking Scheme) alongwith the extensive supervisory checks and counter-checks

through which CBSE tries to ensure objective and fair marking. The present publication is being brought

out with a view to serving the following objectives :

(i) To give an opportunity to the teachers and students to look into the Marking Schemes that

were developed by the Board and supplied to the evaluators in 2012 main examination in

some selected main subjects.

(ii) To receive feedback and suggestions from institutions/subject teachers on the utility and

further improvement of Marking Schemes.

(iii) To encourage institutions to undertake similar exercise of developing marking schemes for

classes other than those covered by the Board's examination with a view to increasing

teachers' responsiveness to them as the essential tools of evaluation.

(iii)


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HOW TO USE

Teachers and the students preparing for Class XII examination of the Board constitute the

primary interest-group of this publication. Marking Schemes of Question Papers in the subjects of

English Core, Functional English, Mathematics, Physics, Chemistry, Biology, Bio-Technology, Informatics

Practices, Computer Science, Engineering Drawing and Multimedia & Web Technology administered

in Delhi and Outside Delhi during the 2012 main examination have been included in this document.

Some tips on their usage are given below :

(a) To Teachers :

--- Go through the syllabus and the weightage distribution for the subject carefully.

--- Read the question paper to find out how far the question paper set subscribes to the

prescribed design. Grade every question by difficulty level for students who have taken themain Board examination.

--- Consult the 'Marking Scheme' for each question, with reference to steps into which answers

and awards have been divided.

--- Work out concrete suggestions for the Board.

(b) To Students :

--- Study each question carefully, comprehend them and write down the main points of theanswer and note down their difficulties for clarification.

--- Examine a question in conjunction with the Marking Scheme and find out the proximity of

the answer to that suggested in the Marking Scheme.

We urge the teachers to encourage their students to make use of this publication

M.C. SHARMA

CONTROLLER OF EXAMINATIONS

(iv)


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CONTENTS

Senior School Certificate Examination (XII)

Marking Scheme

Page No.

1. English Core .............................................................................................................. 1-42

2. Functional English ...................................................................................................... 43-90

3. Mathematics ............................................................................................................. 91-124

4. Physics ...................................................................................................................... 125-181

5. Chemistry .................................................................................................................. 182-214

6. Biology ...................................................................................................................... 215-247

7. Bio-technology .......................................................................................................... 248-262

8. Informatics Practices .................................................................................................. 263-322

9. Computer Science ..................................................................................................... 323-422

10. Engineering Graphics ................................................................................................. 423-448

11. Multimedia and Web Technology ............................................................................... 449-502

(v)


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LIST OF COORDINATORS/SUBJECT EXPERTS/REPRESENTATIVES

OF THE REGIONS FOR UPDATION/FINALISATION OF THE

MARKING SCHEME FOR THE SENIOR SCHOOL CERTIFICATE

EXAMINATION, 2012

S.No. Name of the Coordinator/Subject

Experts


Experts

(vi)

7. Br. Felix Martis

Loyola High School,

Khurji, PO Sadaqat Ashram,

Patna, Bihar

8. Sh. Vikram Joshi

Principal,Jawahar Navodaya Vidyalaya,

Rudrapur,

Udham Singh Nagar,

Utrakhand-263153

9. Mr. S.P. Chand

PGT

Global Gurukul Institute School,

Mani Majra, Chandigarh

10. Mr. D.N.Tiwari

PGT

Laxman Public School

Hauz Khas, New Delhi - 16

11. Shri Dastidar

Principal

Army School, Narangi,

PO-Satgaon,

Guwahati - 781027

12. Ms. Sudesh Arora



13. Sh. Navin Sharma



ENGLISH CORE

1. Dr. Usha Ram

Principal


Hauz Khas, New Delhi-16

2. Dr. Opkar Singh

Retd. Prof.

121, Sahyog Appartments

Mayur Vihar Phase-I

Delhi-110091

3. Mrs. Bella Bhateja,

PGT

G. D. Goenka Pub. School

Vasant Kunj,

New Delhi

4. Dr. Sanjeevan Bose

PGT

Scindia School

The Fort, Gwalior-474008

5. Ms. Vandana Kapoor

Principal

S.L.S. DAV Public School

Mausam Vihar

Delhi

6. Mrs. Kanti Ramakrishnan

Vice Principal

Chinmaya Vidyalaya,

9 B Taylors Road, Kilpauk,

Chennai-600011


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Experts


Experts

(vii)

FUNCTIONAL ENGLISH

1. Mrs. Annie KoshyPrincipal

St. Mary's School

B-II Block, Safdarjung Enclave

New Delhi

2. Mrs. Usha Ram

Principal


Hauz Khas, New Delhi-110016

3. Mrs. Malini KhatriModern School

Barakhamba Road

New Delhi-110001

4. Ms. Neena Kaul

St.Marys School

B-II Block, Safdarjung Enclave

New Delhi

5. Mrs. S. Lahiri

St. Mary's School

B-II Block, Safdarjung Enclave,

New Delhi

6. Lakshmi Srinivasan

Principal,

P. S. Sr. Sec. School,

33, Alarmelmangapuram

Mylapore, Chennai-600004

7. Shri P. J. Peter

PGT

Laxman Public SchoolHauz Khas, New Delhi

8. Mrs. Shailja Jaiswal

PGT

Delhi Public School

Site No. 3, Meerut Road,

Ghaziabad - UP-201003

MATHEMATICS

1. Mrs. Anita SharmaPrincipal

S.D. Public School

BU Block, Pitampura,

Delhi-110034

2. Dr. V. P. Gupta

Retired Professor

Kala Vihar Appartments,

Mayur Vihar, Phase-1

Delhi

3. Sh. G. D. Dhall

K-171, LIC Colony

Syed Nangloi Village

Delhi

4. Sh. S.N. Chibber

Principal (Retd.)

B-330, Saraswati Vihar

Delhi

5. Sh. J. C. Nijhawan

Rtd. Principal

C-51, Maharana Pratap Enclave,

Delhi-110034

6. Mr. Rajpal,

PGT

Pratibha Vikas Vidyalaya,

Gandhi Nagar, Delhi-110051

(218, Maitrye Apptts.

I.P. Extn., Patparganj, Delhi)

7. Sh. M.M. Alam

Vice Principal

St. John's Sr. Sec. School,

Bundi Road,

Kota-324008 (Rajasthan)


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Experts


Experts

(viii)

8. Sh. D. R. Sharma,

Vice-PrincipalJNV, Mouli

Panchkul

9. Sh. Mongal Saha,

Vice Principal,

Army School, Narangi,

PO-Satgaon,

Guwahati-781027

10. Mr. C. Sathyamurthy

Principal

Chinmaya Vidyalaya

9-B, Taylore Road

Kilpauk Chennai-600010

11. Sh. S. D. Arora,

Principal,

Kendriya Vidyalaya No.1Civil Lines,

Rae Bareli, U.P.-2299001

12. Mrs. Saroj Gupta,

Principal,

DTEA Sr. Sec. School,

Sector-4, R.K. Puram,

Delhi

13. Sh. R.N. Chaubey

Jawahar Lal Memorial

Sr. Sec. School

Digwadih No. 12,

P.O. Pathardih, Dhanbad,

Jharkhand

14. Dr. K.C. Satpathy

Principal,DAV Pub, School,

Chandrasekharpur,

Bhubaneshwar, Khordha

Odisha-751021

15. Sh. V.P. Singh

Retired Principal

2610 A, Street No.9

Bihari Colony Shahdara,

Delhi-32

16. Sh. J.P. Singh

A-64, F-3, Ram Prastha

Ghaziabad (U.P)

17. Sh. Parveen Kumar

PGT

S. D. Public School,

BU Block, PitampuraDelhi

18. Sh. Ajay Marwaha

PGT (Mathematics)

S.D. Public School

BU Block

Pitampura, Delhi

PHYSICS

1. Sh. D.K. Bedi

Principal

Apeejay School,

Road No. 42, Sainik Vihar,

Pitampura

Delhi-110034


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Experts


Experts

(ix)

2. Prof. V.S. Bhasin

B4/46 Paschim Vihar,New Delhi

3. Sh. N.K. Sehgal

A-94/1, SFS Flats,

Saket, New Delhi

4. Sh. G. Giri

Head Master

Modern School

Barakhamba Road

New Delhi

5. Sh. Suraj Prakash

Retd. Principal

QU-290 - B,

Chitrakoot Apptts.

Pitampura Delhi - 110034

6. Sh. R.S. Thakur,

Vice Principal

HE Vikram Hr. Sec. School,BHEL, Piplani

Bhopal - 462021

7. Mr. L. Neelakanta Pillai,

Principal

Kola Perumal Chetty Vaishnav

Sr. Sec. School

815, EVR Periyar High Road,

Arumbakkam

Chennai, 600106

8. Mr. Dinesh Bartwal,

Vice Principal

Doon International School,

32, Curzon Road Dalanwala

Dehradun

Uttrakhand-248001

9. Sh. Nilakantha Panigrahi

Vice PrincipalSai International School,

5A, Chandaka Indust. Estate,

Infocity Road, Bhubaneshwar.

Khurda, Bhubaneswar (Odisha)

10. Sh. Surjan Singh

PGT

CRPF Public School,

Sector-XIV, Rohini,

Delhi-110085

11. Mrs. Kiran Nayak

Apeejay School,

Road No. 42,

Sainik Vihar, Pitampura

Delhi

12. Mrs. Ravinder Kaur

PGT

Govt. Model Sr. Sec. School

Sector 33

Chandigarh

CHEMISTRY

1. Sh.S.K.Munjal

Principal

St. Margaret Pub. School

D-Block Prashant Vihar

Delhi-110085

2. Dr. K.N. Uppadhyay,

326 SFS FlatsAshok Vihar Phase-IV

Delhi-52

3. Prof. R.D. Shukla,

40, Delux Apptt.

B-5, Vasundhara Enclave

Delhi-110096


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Experts


Experts

(x)

4. Mr. D.A. Mishra

Retd. PrincipalB-203, Saraswati Vihar,

Delhi-110034

5. Sh. Rakesh Dhawan

PGT

St. Margaret Public School

Prashant Vihar

Delhi

6. Sh. Deshbir Singh,

PGT

St. Paul's Hr Sec. School

Boundary Road,

Indore-452001

7. Sh. Avinash Kumar Vohra

PGT


Sector-35, Chandigarh

8. Sh. R.C. GondPrincipal

Kendriya Vidyalaya No. 2,

Itanagar, Distt. Pampumpare,

Arunachal Pradesh-791111.

9. Mr. K.M. Abdul Raheem

Vice Principal

SPDH Sindhi Model Sr. Sec. School

1, Danodara Street

Kellys, ChennaiTamilnadu-600010

10. Sh. A.N. Pandit

Principal

Godwin Public School

Rohta Road, P.O. Fazalpur

Meerut (U.P.) - 250001

11. Dr. (Mrs) Sangeeta Bhatia

PrincipalKIIT World School

Pitampura, Near Club,

Delhi-34

12. Dr. D.R. Singh

Jawahar Vidya Mandir

Shyamli, Ranchi,

Jharkhand

13. Dr. Mrs. Bhagwati Nayak

Principal

DAV Public School, Unit-8,

Post office Naya Palli

Bhubneshwar-751012 (Odisha)

BIOLOGY

1. Mrs. Rachna Gupta,

Headmistress

Delhi Public SchoolSector C Poket 5,

Vasant Kunj, New Delhi

2. Sh. Y.P. Purang

Retd. ADE

C2/113, Janakpuri,

New Delhi-58

3. Mrs.Rita Talwar

Retd. Principal

54, Khan Market

New Delhi

4. Sh. Virendra Srivastava

B-3B/95 B

Janakpuri

New Delhi-110058


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Experts


Experts

(xi)

5. Ms. Shivani Goswami,

563, Golf Vista Apptts,Alpha-II, Sector, Greater Noida,

Gautam Budh Nagar (U.P.)

6. Smt. Kamaljeet Kaur

PGT


Sector-18

Chandigarh

7. Sh. Laxmi Narayanan,

Principal,

Kendriya Vidyalaya, AFS,

Digaru, Sonapur, Kamrup,

Assam-782402

8. Mrs. Margarette Davidraj

Principal

Bakthavatsalam Vidyashram

14, 31st Street, TNHB Colony,

Periyaar Nagar, Korattur,

Chennai-80

9. Smt. Neeta Rastogi

Principal

Sadhu Vaswani Int. School for Girls

2nd Street, Shanti Niketan

New Delhi

10. Dr. U.S. Prasad

DAV Public School

Cantonment Area,

Gaya (Bihar)

11. Sh. Shankar Bardhan,

Vice Principal,

Hem Sheela Model School

Jawahar Lal Nehru Avenue,

Durgapur, Barddhaman,

West Bengal-713214

12. Ms. Bandana Lazarus

Delhi Public School,Vasant Kunj,

New Delhi-70

13. Sh. S. K. Joshi

Principal

Vidya Sagar School

Bichili Mardana

Indore, Madhya Pradesh

BIO-TECHNOLOGY

1. Dr. K. Nirmala

Reader

Department of Bio-Chemistry

Daulat Ram College

University of Delhi

3. Dr. J.S. Virdi

Department of Microbiology

University of Delhi

South Campus

Benito Juarez Road, Dhaula Kuan

New Delhi

3. Smt. Madhumati Bhaskarwar

PGT

G.D. Goenka Public School

Sector 3, Pocket - 8 & 9

Vasant Kunj, New Delhi

4. Ms. Vaishali Aggarwal

PGT-Bio-Technology,

SLS DAV Public School

Mausam Vihar

Delhi


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Experts


Experts

(xii)

5. Ms. Shashi Bajaj,

B-278, Saraswati Vihar,

Pitampura

New Delhi

6. Dr. Sunita Joshi,

Deptt. of Biochem.

DRC, Delhi University.

7. Mrs. Chhonkan,

Delhi Public School,

R.K. Puram

Sector-XII,

New Delhi

8. Mrs. Shikha Gupta

JD Tytler School

New Rajendra Nagar,

New Delhi.

INFORMATICS PRACTICE

1. Sh. Mukesh Kumar

PGT

Delhi Public School

Sec-XII, R.K. Puram,

New Delhi

2. Sh. M.P.S. Bhatia

NSIT

Dwarka, Delhi

3. Sh. R.K. Tiwari

PGT

Vivekanand School

D Block, Anand Vihar

Delhi

4. Dr. Richa Verma

PGT

KIIT World School

Near Club

Pitampura, Delhi

5. Mrs. Nancy Sehgal

PGT

Mata Jai Kaur Public School

Ashok Vihar,

Delhi

6. Mrs. Bharti Arora

PGT.

S.D. Public School

Sector-32, Chandigarh

7. Mr. K.V. Krishan Kumar

PGT

PS Sr. Sec. School

33, Almelmangapuram

Mylapore, Chennai-600004

COMPUTER SCIENCE

1. Sh.Mukesh Kumar

PGT

Delhi Public School

See-XII, R.K.Puram

New Delhi


NSIT

Dwarka, Delhi


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Experts


Experts

(xiii)

3. Sh. R.K. Tiwari

PGTVivekanand School

D Block, Anand Vihar

Delhi

4. Mrs. Sushila Mohan Dass

3043, Shobha Amethyst,

Whitefield Main Road,

Bangalore

5. Sh. Mohitendra Dey

Delhi Public School

RK Puram, Sector-12

New Delhi-110022

6. Sh. S. Sriram

HOD

Mayo College

Ajmer, Rajasthan-305008

7. Smt. Manjeet Johar

PGT

Global Gurukul Int. School,

I.T. Park, Mani Majra,

Chandigarh

8. Mrs. Usha VishwanathanPGT

Sri Sankara Sr. Sec. School,

No. 9/21 Vasantha Press Road,

Adyar, Chennai

Tamilnadu-600020

9. Smt. Divya Jain

74, Jai Apartments

I P Extension

Delhi-92

10. Ms. Purvi Srivastava

Ganga International School

Hiran Kudna, Rohtak Road,

New Delhi-110041

11. Shri Ashok Kumar Goel

ED-50A, Pitampura

Delhi

ENGINEERING GRAPHICS

1. Mr. R.K. Gupta

Head of the School

Jain Sr. Sec. School

Daryaganj

New Delhi

2. Sh. Arvind Kumar Singh Chauhan

Modern School

Vasant Vihar

New Delhi

3. Prof. N. L. Sachdeva

Rtd. Prof. from DCE

52-D, BW Block

Shalimar Bagh

Delhi


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Experts


Experts

(xiv)

4. Sh.R.P Chaurasiya

Vice Principal (Retd.)

61/B-7, Sector-04, Rohini

5. Sh. Hitesh Gupta

G.B. Pant S.B. Vidyalaya

Sriniwaspuri

New Delhi

6. Sh. Surjit Chatterjee

Bal Bharti Pub. School

Ganga Ram Hospital Marg

New Delhi

MULTIMEDIA & WEB TECHNOLOGY

1. Sh. Mukesh Kumar

Delhi Public School

Sector-XII, R.K. Puram

New Delhi

2. Smt. Gurpreet Kaur

G.D. Goenka Public School

Vasant Vihar

New Delhi


NSIT, Sector-3

Dwarka, Delhi

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