CBSE Board Paper 2023 (Marking Scheme and Solutions) | Chemistry Class 12 - NEET PDF Download

 Page 1


 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only)  
Senior Secondary School Examination,2023. 
SUBJECT: CHEMISTRY (043) (56/1/1) 
General Instructions: - 
1 You are aware that evaluation is the most important process in the actual and 
correct assessment of the candidates. A small mistake in evaluation may lead 
to serious problems which may affect the future of the candidates, education 
system and teaching profession. To avoid mistakes, it is requested that before 
starting evaluation, you must read and understand the spot evaluation 
guidelines carefully. 
2 “Evaluation policy is a confidential policy as it is related to the 
confidentiality of the examinations conducted, Evaluation done and 
several other aspects. Its’ leakage to public in any manner could lead to 
derailment of the examination system and affect the life and future of 
millions of candidates. Sharing this policy/document to anyone, 
publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3 Evaluation is to be done as per instructions provided in the Marking Scheme. It 
should not be done according to one’s own interpretation or any other 
consideration. Marking Scheme should be strictly adhered to and religiously 
followed. However, while evaluating, answers which are based on latest 
information or knowledge and/or are innovative, they may be assessed 
for their correctness otherwise and due marks be awarded to them. In 
class-XII, while evaluating two competency-based questions, please try to 
understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks 
should be awarded. 
4 The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete 
answer. The students can have their own expression and if the expression is 
correct, the due marks should be awarded accordingly. 
5 The Head-Examiner must go through the first five answer books evaluated by 
each evaluator on the first day, to ensure that evaluation has been carried out 
as per the instructions given in the Marking Scheme. If there is any variation, 
the same should be zero after delibration and discussion. The remaining 
answer books meant for evaluation shall be given only after ensuring that there 
is no significant variation in the marking of individual evaluators. 
6 Evaluators will mark( v ) wherever answer is correct. For wrong answer 
CROSS ‘X” be marked. Evaluators will not put right ( ?)while evaluating which 
gives an impression that answer is correct and no marks are awarded. This is 
most common mistake which evaluators are committing. 
7 If a question has parts, please award marks on the right-hand side for each 
part. Marks awarded for different parts of the question should then be totaled 
up and written in the left-hand margin and encircled. This may be followed 
strictly. 
8 If a question does not have any parts, marks must be awarded in the left-hand 
margin and encircled. This may also be followed strictly. 
Page 2


 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only)  
Senior Secondary School Examination,2023. 
SUBJECT: CHEMISTRY (043) (56/1/1) 
General Instructions: - 
1 You are aware that evaluation is the most important process in the actual and 
correct assessment of the candidates. A small mistake in evaluation may lead 
to serious problems which may affect the future of the candidates, education 
system and teaching profession. To avoid mistakes, it is requested that before 
starting evaluation, you must read and understand the spot evaluation 
guidelines carefully. 
2 “Evaluation policy is a confidential policy as it is related to the 
confidentiality of the examinations conducted, Evaluation done and 
several other aspects. Its’ leakage to public in any manner could lead to 
derailment of the examination system and affect the life and future of 
millions of candidates. Sharing this policy/document to anyone, 
publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3 Evaluation is to be done as per instructions provided in the Marking Scheme. It 
should not be done according to one’s own interpretation or any other 
consideration. Marking Scheme should be strictly adhered to and religiously 
followed. However, while evaluating, answers which are based on latest 
information or knowledge and/or are innovative, they may be assessed 
for their correctness otherwise and due marks be awarded to them. In 
class-XII, while evaluating two competency-based questions, please try to 
understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks 
should be awarded. 
4 The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete 
answer. The students can have their own expression and if the expression is 
correct, the due marks should be awarded accordingly. 
5 The Head-Examiner must go through the first five answer books evaluated by 
each evaluator on the first day, to ensure that evaluation has been carried out 
as per the instructions given in the Marking Scheme. If there is any variation, 
the same should be zero after delibration and discussion. The remaining 
answer books meant for evaluation shall be given only after ensuring that there 
is no significant variation in the marking of individual evaluators. 
6 Evaluators will mark( v ) wherever answer is correct. For wrong answer 
CROSS ‘X” be marked. Evaluators will not put right ( ?)while evaluating which 
gives an impression that answer is correct and no marks are awarded. This is 
most common mistake which evaluators are committing. 
7 If a question has parts, please award marks on the right-hand side for each 
part. Marks awarded for different parts of the question should then be totaled 
up and written in the left-hand margin and encircled. This may be followed 
strictly. 
8 If a question does not have any parts, marks must be awarded in the left-hand 
margin and encircled. This may also be followed strictly. 
XII_39_043_56/1/1_Chemistry # Page-2 
 
9 If a student has attempted an extra question, answer of the question deserving 
more marks should be retained and the other answer scored out with a note 
“Extra Question”. 
10 No marks to be deducted for the cumulative effect of an error. It should be 
penalized only once. 
11 A full scale of marks 70 has to be used. Please do not hesitate to award full 
marks if the answer deserves it. 
12 Every examiner has to necessarily do evaluation work for full working hours 
i.e., 8 hours every day and evaluate 20 answer books per day in main subjects 
and 25 answer books per day in other subjects (Details are given in Spot 
Guidelines).This is in view of the reduced syllabus and number of questions in 
question paper. 
13 Ensure that you do not make the following common types of errors committed 
by the Examiner in the past:- 
? Leaving answer or part thereof unassessed in an answer book. 
? Giving more marks for an answer than assigned to it. 
? Wrong totaling of marks awarded on an answer. 
? Wrong transfer of marks from the inside pages of the answer book to the 
title page. 
? Wrong question wise totaling on the title page. 
? Wrong totaling of marks of the two columns on the title page. 
? Wrong grand total. 
? Marks in words and figures not tallying/not same. 
? Wrong transfer of marks from the answer book to online award list. 
? Answers marked as correct, but marks not awarded. (Ensure that the right 
tick mark is correctly and clearly indicated. It should merely be a line. 
Same is with the X for incorrect answer.) 
? Half or a part of answer marked correct and the rest as wrong, but no 
marks awarded. 
14 While evaluating the answer books if the answer is found to be totally incorrect, 
it should be marked as cross (X) and awarded zero (0)Marks. 
15 Any un assessed portion, non-carrying over of marks to the title page, or 
totaling error detected by the candidate shall damage the prestige of all the 
personnel engaged in the evaluation work as also of the Board. Hence, in order 
to uphold the prestige of all concerned, it is again reiterated that the 
instructions be followed meticulously and judiciously. 
16 The Examiners should acquaint themselves with the guidelines given in the 
“Guidelines for spot Evaluation” before starting the actual evaluation. 
17 Every Examiner shall also ensure that all the answers are evaluated, marks 
carried over to the title page, correctly totaled and written in figures and words. 
18 The candidates are entitled to obtain photocopy of the Answer Book on request 
on payment of the prescribed processing fee. All Examiners/Additional Head 
Examiners/Head Examiners are once again reminded that they must ensure 
that evaluation is carried out strictly as per value points for each answer as 
given in the Marking Scheme. 
 
 
 
 
 
Page 3


 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only)  
Senior Secondary School Examination,2023. 
SUBJECT: CHEMISTRY (043) (56/1/1) 
General Instructions: - 
1 You are aware that evaluation is the most important process in the actual and 
correct assessment of the candidates. A small mistake in evaluation may lead 
to serious problems which may affect the future of the candidates, education 
system and teaching profession. To avoid mistakes, it is requested that before 
starting evaluation, you must read and understand the spot evaluation 
guidelines carefully. 
2 “Evaluation policy is a confidential policy as it is related to the 
confidentiality of the examinations conducted, Evaluation done and 
several other aspects. Its’ leakage to public in any manner could lead to 
derailment of the examination system and affect the life and future of 
millions of candidates. Sharing this policy/document to anyone, 
publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3 Evaluation is to be done as per instructions provided in the Marking Scheme. It 
should not be done according to one’s own interpretation or any other 
consideration. Marking Scheme should be strictly adhered to and religiously 
followed. However, while evaluating, answers which are based on latest 
information or knowledge and/or are innovative, they may be assessed 
for their correctness otherwise and due marks be awarded to them. In 
class-XII, while evaluating two competency-based questions, please try to 
understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks 
should be awarded. 
4 The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete 
answer. The students can have their own expression and if the expression is 
correct, the due marks should be awarded accordingly. 
5 The Head-Examiner must go through the first five answer books evaluated by 
each evaluator on the first day, to ensure that evaluation has been carried out 
as per the instructions given in the Marking Scheme. If there is any variation, 
the same should be zero after delibration and discussion. The remaining 
answer books meant for evaluation shall be given only after ensuring that there 
is no significant variation in the marking of individual evaluators. 
6 Evaluators will mark( v ) wherever answer is correct. For wrong answer 
CROSS ‘X” be marked. Evaluators will not put right ( ?)while evaluating which 
gives an impression that answer is correct and no marks are awarded. This is 
most common mistake which evaluators are committing. 
7 If a question has parts, please award marks on the right-hand side for each 
part. Marks awarded for different parts of the question should then be totaled 
up and written in the left-hand margin and encircled. This may be followed 
strictly. 
8 If a question does not have any parts, marks must be awarded in the left-hand 
margin and encircled. This may also be followed strictly. 
XII_39_043_56/1/1_Chemistry # Page-2 
 
9 If a student has attempted an extra question, answer of the question deserving 
more marks should be retained and the other answer scored out with a note 
“Extra Question”. 
10 No marks to be deducted for the cumulative effect of an error. It should be 
penalized only once. 
11 A full scale of marks 70 has to be used. Please do not hesitate to award full 
marks if the answer deserves it. 
12 Every examiner has to necessarily do evaluation work for full working hours 
i.e., 8 hours every day and evaluate 20 answer books per day in main subjects 
and 25 answer books per day in other subjects (Details are given in Spot 
Guidelines).This is in view of the reduced syllabus and number of questions in 
question paper. 
13 Ensure that you do not make the following common types of errors committed 
by the Examiner in the past:- 
? Leaving answer or part thereof unassessed in an answer book. 
? Giving more marks for an answer than assigned to it. 
? Wrong totaling of marks awarded on an answer. 
? Wrong transfer of marks from the inside pages of the answer book to the 
title page. 
? Wrong question wise totaling on the title page. 
? Wrong totaling of marks of the two columns on the title page. 
? Wrong grand total. 
? Marks in words and figures not tallying/not same. 
? Wrong transfer of marks from the answer book to online award list. 
? Answers marked as correct, but marks not awarded. (Ensure that the right 
tick mark is correctly and clearly indicated. It should merely be a line. 
Same is with the X for incorrect answer.) 
? Half or a part of answer marked correct and the rest as wrong, but no 
marks awarded. 
14 While evaluating the answer books if the answer is found to be totally incorrect, 
it should be marked as cross (X) and awarded zero (0)Marks. 
15 Any un assessed portion, non-carrying over of marks to the title page, or 
totaling error detected by the candidate shall damage the prestige of all the 
personnel engaged in the evaluation work as also of the Board. Hence, in order 
to uphold the prestige of all concerned, it is again reiterated that the 
instructions be followed meticulously and judiciously. 
16 The Examiners should acquaint themselves with the guidelines given in the 
“Guidelines for spot Evaluation” before starting the actual evaluation. 
17 Every Examiner shall also ensure that all the answers are evaluated, marks 
carried over to the title page, correctly totaled and written in figures and words. 
18 The candidates are entitled to obtain photocopy of the Answer Book on request 
on payment of the prescribed processing fee. All Examiners/Additional Head 
Examiners/Head Examiners are once again reminded that they must ensure 
that evaluation is carried out strictly as per value points for each answer as 
given in the Marking Scheme. 
 
 
 
 
 
XII_39_043_56/1/1_Chemistry # Page-3 
 
MARKING SCHEME 
Senior Secondary School Examination, 2023 
CHEMISTRY (Subject Code –043) 
[ Paper Code: 56/1/1] 
 
Q. No. EXPECTED ANSWER / VALUE POINTS Marks 
 
SECTION-A 
 
1. (a) 1 
2. 
(c) 
1 
3. (d)  1 
4.  (c) 1 
5. (c) 1 
6. (c) / Full mark to be awarded for any option 1 
7. (b)  1 
8. (c)  1 
9. (b) 1 
10. (a) 1 
11. (b) 1 
12. (c) 1 
13. (c) / Award full mark if attempted (Printing error) 1 
14. (c) 1 
15. (b) 1 
16. (c) 1 
17. (a) 1 
18. (a) 1 
 SECTION- B  
19. Henry’s law states that the partial vapour pressure of a gas is directly proportional to 
the mole fraction of the gas in the solution  / p = K
H
 x     where p = partial pressure 
of gas, x = mole fraction in solution, and k
H
 is Henry’s constant.   
Application:  
To increase the solubility of CO
2
 in soft drinks and soda water, the bottle is 
sealed under high pressure / to minimize the painful effects accompanying the 
1  
 
 
 
Page 4


 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only)  
Senior Secondary School Examination,2023. 
SUBJECT: CHEMISTRY (043) (56/1/1) 
General Instructions: - 
1 You are aware that evaluation is the most important process in the actual and 
correct assessment of the candidates. A small mistake in evaluation may lead 
to serious problems which may affect the future of the candidates, education 
system and teaching profession. To avoid mistakes, it is requested that before 
starting evaluation, you must read and understand the spot evaluation 
guidelines carefully. 
2 “Evaluation policy is a confidential policy as it is related to the 
confidentiality of the examinations conducted, Evaluation done and 
several other aspects. Its’ leakage to public in any manner could lead to 
derailment of the examination system and affect the life and future of 
millions of candidates. Sharing this policy/document to anyone, 
publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3 Evaluation is to be done as per instructions provided in the Marking Scheme. It 
should not be done according to one’s own interpretation or any other 
consideration. Marking Scheme should be strictly adhered to and religiously 
followed. However, while evaluating, answers which are based on latest 
information or knowledge and/or are innovative, they may be assessed 
for their correctness otherwise and due marks be awarded to them. In 
class-XII, while evaluating two competency-based questions, please try to 
understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks 
should be awarded. 
4 The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete 
answer. The students can have their own expression and if the expression is 
correct, the due marks should be awarded accordingly. 
5 The Head-Examiner must go through the first five answer books evaluated by 
each evaluator on the first day, to ensure that evaluation has been carried out 
as per the instructions given in the Marking Scheme. If there is any variation, 
the same should be zero after delibration and discussion. The remaining 
answer books meant for evaluation shall be given only after ensuring that there 
is no significant variation in the marking of individual evaluators. 
6 Evaluators will mark( v ) wherever answer is correct. For wrong answer 
CROSS ‘X” be marked. Evaluators will not put right ( ?)while evaluating which 
gives an impression that answer is correct and no marks are awarded. This is 
most common mistake which evaluators are committing. 
7 If a question has parts, please award marks on the right-hand side for each 
part. Marks awarded for different parts of the question should then be totaled 
up and written in the left-hand margin and encircled. This may be followed 
strictly. 
8 If a question does not have any parts, marks must be awarded in the left-hand 
margin and encircled. This may also be followed strictly. 
XII_39_043_56/1/1_Chemistry # Page-2 
 
9 If a student has attempted an extra question, answer of the question deserving 
more marks should be retained and the other answer scored out with a note 
“Extra Question”. 
10 No marks to be deducted for the cumulative effect of an error. It should be 
penalized only once. 
11 A full scale of marks 70 has to be used. Please do not hesitate to award full 
marks if the answer deserves it. 
12 Every examiner has to necessarily do evaluation work for full working hours 
i.e., 8 hours every day and evaluate 20 answer books per day in main subjects 
and 25 answer books per day in other subjects (Details are given in Spot 
Guidelines).This is in view of the reduced syllabus and number of questions in 
question paper. 
13 Ensure that you do not make the following common types of errors committed 
by the Examiner in the past:- 
? Leaving answer or part thereof unassessed in an answer book. 
? Giving more marks for an answer than assigned to it. 
? Wrong totaling of marks awarded on an answer. 
? Wrong transfer of marks from the inside pages of the answer book to the 
title page. 
? Wrong question wise totaling on the title page. 
? Wrong totaling of marks of the two columns on the title page. 
? Wrong grand total. 
? Marks in words and figures not tallying/not same. 
? Wrong transfer of marks from the answer book to online award list. 
? Answers marked as correct, but marks not awarded. (Ensure that the right 
tick mark is correctly and clearly indicated. It should merely be a line. 
Same is with the X for incorrect answer.) 
? Half or a part of answer marked correct and the rest as wrong, but no 
marks awarded. 
14 While evaluating the answer books if the answer is found to be totally incorrect, 
it should be marked as cross (X) and awarded zero (0)Marks. 
15 Any un assessed portion, non-carrying over of marks to the title page, or 
totaling error detected by the candidate shall damage the prestige of all the 
personnel engaged in the evaluation work as also of the Board. Hence, in order 
to uphold the prestige of all concerned, it is again reiterated that the 
instructions be followed meticulously and judiciously. 
16 The Examiners should acquaint themselves with the guidelines given in the 
“Guidelines for spot Evaluation” before starting the actual evaluation. 
17 Every Examiner shall also ensure that all the answers are evaluated, marks 
carried over to the title page, correctly totaled and written in figures and words. 
18 The candidates are entitled to obtain photocopy of the Answer Book on request 
on payment of the prescribed processing fee. All Examiners/Additional Head 
Examiners/Head Examiners are once again reminded that they must ensure 
that evaluation is carried out strictly as per value points for each answer as 
given in the Marking Scheme. 
 
 
 
 
 
XII_39_043_56/1/1_Chemistry # Page-3 
 
MARKING SCHEME 
Senior Secondary School Examination, 2023 
CHEMISTRY (Subject Code –043) 
[ Paper Code: 56/1/1] 
 
Q. No. EXPECTED ANSWER / VALUE POINTS Marks 
 
SECTION-A 
 
1. (a) 1 
2. 
(c) 
1 
3. (d)  1 
4.  (c) 1 
5. (c) 1 
6. (c) / Full mark to be awarded for any option 1 
7. (b)  1 
8. (c)  1 
9. (b) 1 
10. (a) 1 
11. (b) 1 
12. (c) 1 
13. (c) / Award full mark if attempted (Printing error) 1 
14. (c) 1 
15. (b) 1 
16. (c) 1 
17. (a) 1 
18. (a) 1 
 SECTION- B  
19. Henry’s law states that the partial vapour pressure of a gas is directly proportional to 
the mole fraction of the gas in the solution  / p = K
H
 x     where p = partial pressure 
of gas, x = mole fraction in solution, and k
H
 is Henry’s constant.   
Application:  
To increase the solubility of CO
2
 in soft drinks and soda water, the bottle is 
sealed under high pressure / to minimize the painful effects accompanying the 
1  
 
 
 
XII_39_043_56/1/1_Chemistry # Page-4 
 
decompression of deep-sea divers (bends). Oxygen diluted with less soluble 
helium gas is used for breathing / At higher altitudes, low blood oxygen causes 
climbers to become weak and unable to think clearly (anoxia).               (Any one) 
                                                                                (or any other correct application)  
 
1 
 
20. ‘B’ is a strong electrolyte. 
                       
1 
 
 
 
 
1 
 
 
 
 
 
                                                     OR 
         A = ?r
2
 = 3·14 ? (0·5)
2 
= 0·785 cm
2
 ,  l = 50 cm 
        k = 
l
??  × ??  
           = 
50
0·785 ?? ( 5.55 ?? 10
3
)  
  
           = 11·47 X 10
-3
 S cm
-1 
                      
                                                                     (or by any other correct method) 
 
 
 
½  
 
1 
 
½ 
  
 
21. 
(a)    2 Mn?? ?? -
  +  5 N
–
2
O  + 6 H
+
 ? ? ? 2 Mn
2+
 + 5 N
–
3
O +  3 H
2
O 
(b)   Cr
2
– 2
7
O   +  14 H
+
  +  6 e
–
       ? ? ?  2 Cr
3+
 + 7 H
2
O 
1 
 
1 
22. 
(a)    A  =         CH
3
 – 
l C
|
CH – CH
3           /     2-Chloropropane  
       
(b)   A    =        CH
3
 – CH = CH
2
           / Propene 
        B     =        CH
3
 – – CH
3          / 2-Bromopropane
 
½ x 4 
 
 
 
 
 
 
 
23. (a)  
(i) Because phenoxide ion is more stable due to resonance than alkoxide ion.   
                                                                                (or any other correct explanation) 
(ii) Because branching decreases the surface area / the van der Waals force decreases 
with a decrease in surface area. 
1 
 
1 
                                                       OR  
Br
|
CH
Page 5


 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only)  
Senior Secondary School Examination,2023. 
SUBJECT: CHEMISTRY (043) (56/1/1) 
General Instructions: - 
1 You are aware that evaluation is the most important process in the actual and 
correct assessment of the candidates. A small mistake in evaluation may lead 
to serious problems which may affect the future of the candidates, education 
system and teaching profession. To avoid mistakes, it is requested that before 
starting evaluation, you must read and understand the spot evaluation 
guidelines carefully. 
2 “Evaluation policy is a confidential policy as it is related to the 
confidentiality of the examinations conducted, Evaluation done and 
several other aspects. Its’ leakage to public in any manner could lead to 
derailment of the examination system and affect the life and future of 
millions of candidates. Sharing this policy/document to anyone, 
publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3 Evaluation is to be done as per instructions provided in the Marking Scheme. It 
should not be done according to one’s own interpretation or any other 
consideration. Marking Scheme should be strictly adhered to and religiously 
followed. However, while evaluating, answers which are based on latest 
information or knowledge and/or are innovative, they may be assessed 
for their correctness otherwise and due marks be awarded to them. In 
class-XII, while evaluating two competency-based questions, please try to 
understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks 
should be awarded. 
4 The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete 
answer. The students can have their own expression and if the expression is 
correct, the due marks should be awarded accordingly. 
5 The Head-Examiner must go through the first five answer books evaluated by 
each evaluator on the first day, to ensure that evaluation has been carried out 
as per the instructions given in the Marking Scheme. If there is any variation, 
the same should be zero after delibration and discussion. The remaining 
answer books meant for evaluation shall be given only after ensuring that there 
is no significant variation in the marking of individual evaluators. 
6 Evaluators will mark( v ) wherever answer is correct. For wrong answer 
CROSS ‘X” be marked. Evaluators will not put right ( ?)while evaluating which 
gives an impression that answer is correct and no marks are awarded. This is 
most common mistake which evaluators are committing. 
7 If a question has parts, please award marks on the right-hand side for each 
part. Marks awarded for different parts of the question should then be totaled 
up and written in the left-hand margin and encircled. This may be followed 
strictly. 
8 If a question does not have any parts, marks must be awarded in the left-hand 
margin and encircled. This may also be followed strictly. 
XII_39_043_56/1/1_Chemistry # Page-2 
 
9 If a student has attempted an extra question, answer of the question deserving 
more marks should be retained and the other answer scored out with a note 
“Extra Question”. 
10 No marks to be deducted for the cumulative effect of an error. It should be 
penalized only once. 
11 A full scale of marks 70 has to be used. Please do not hesitate to award full 
marks if the answer deserves it. 
12 Every examiner has to necessarily do evaluation work for full working hours 
i.e., 8 hours every day and evaluate 20 answer books per day in main subjects 
and 25 answer books per day in other subjects (Details are given in Spot 
Guidelines).This is in view of the reduced syllabus and number of questions in 
question paper. 
13 Ensure that you do not make the following common types of errors committed 
by the Examiner in the past:- 
? Leaving answer or part thereof unassessed in an answer book. 
? Giving more marks for an answer than assigned to it. 
? Wrong totaling of marks awarded on an answer. 
? Wrong transfer of marks from the inside pages of the answer book to the 
title page. 
? Wrong question wise totaling on the title page. 
? Wrong totaling of marks of the two columns on the title page. 
? Wrong grand total. 
? Marks in words and figures not tallying/not same. 
? Wrong transfer of marks from the answer book to online award list. 
? Answers marked as correct, but marks not awarded. (Ensure that the right 
tick mark is correctly and clearly indicated. It should merely be a line. 
Same is with the X for incorrect answer.) 
? Half or a part of answer marked correct and the rest as wrong, but no 
marks awarded. 
14 While evaluating the answer books if the answer is found to be totally incorrect, 
it should be marked as cross (X) and awarded zero (0)Marks. 
15 Any un assessed portion, non-carrying over of marks to the title page, or 
totaling error detected by the candidate shall damage the prestige of all the 
personnel engaged in the evaluation work as also of the Board. Hence, in order 
to uphold the prestige of all concerned, it is again reiterated that the 
instructions be followed meticulously and judiciously. 
16 The Examiners should acquaint themselves with the guidelines given in the 
“Guidelines for spot Evaluation” before starting the actual evaluation. 
17 Every Examiner shall also ensure that all the answers are evaluated, marks 
carried over to the title page, correctly totaled and written in figures and words. 
18 The candidates are entitled to obtain photocopy of the Answer Book on request 
on payment of the prescribed processing fee. All Examiners/Additional Head 
Examiners/Head Examiners are once again reminded that they must ensure 
that evaluation is carried out strictly as per value points for each answer as 
given in the Marking Scheme. 
 
 
 
 
 
XII_39_043_56/1/1_Chemistry # Page-3 
 
MARKING SCHEME 
Senior Secondary School Examination, 2023 
CHEMISTRY (Subject Code –043) 
[ Paper Code: 56/1/1] 
 
Q. No. EXPECTED ANSWER / VALUE POINTS Marks 
 
SECTION-A 
 
1. (a) 1 
2. 
(c) 
1 
3. (d)  1 
4.  (c) 1 
5. (c) 1 
6. (c) / Full mark to be awarded for any option 1 
7. (b)  1 
8. (c)  1 
9. (b) 1 
10. (a) 1 
11. (b) 1 
12. (c) 1 
13. (c) / Award full mark if attempted (Printing error) 1 
14. (c) 1 
15. (b) 1 
16. (c) 1 
17. (a) 1 
18. (a) 1 
 SECTION- B  
19. Henry’s law states that the partial vapour pressure of a gas is directly proportional to 
the mole fraction of the gas in the solution  / p = K
H
 x     where p = partial pressure 
of gas, x = mole fraction in solution, and k
H
 is Henry’s constant.   
Application:  
To increase the solubility of CO
2
 in soft drinks and soda water, the bottle is 
sealed under high pressure / to minimize the painful effects accompanying the 
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XII_39_043_56/1/1_Chemistry # Page-4 
 
decompression of deep-sea divers (bends). Oxygen diluted with less soluble 
helium gas is used for breathing / At higher altitudes, low blood oxygen causes 
climbers to become weak and unable to think clearly (anoxia).               (Any one) 
                                                                                (or any other correct application)  
 
1 
 
20. ‘B’ is a strong electrolyte. 
                       
1 
 
 
 
 
1 
 
 
 
 
 
                                                     OR 
         A = ?r
2
 = 3·14 ? (0·5)
2 
= 0·785 cm
2
 ,  l = 50 cm 
        k = 
l
??  × ??  
           = 
50
0·785 ?? ( 5.55 ?? 10
3
)  
  
           = 11·47 X 10
-3
 S cm
-1 
                      
                                                                     (or by any other correct method) 
 
 
 
½  
 
1 
 
½ 
  
 
21. 
(a)    2 Mn?? ?? -
  +  5 N
–
2
O  + 6 H
+
 ? ? ? 2 Mn
2+
 + 5 N
–
3
O +  3 H
2
O 
(b)   Cr
2
– 2
7
O   +  14 H
+
  +  6 e
–
       ? ? ?  2 Cr
3+
 + 7 H
2
O 
1 
 
1 
22. 
(a)    A  =         CH
3
 – 
l C
|
CH – CH
3           /     2-Chloropropane  
       
(b)   A    =        CH
3
 – CH = CH
2
           / Propene 
        B     =        CH
3
 – – CH
3          / 2-Bromopropane
 
½ x 4 
 
 
 
 
 
 
 
23. (a)  
(i) Because phenoxide ion is more stable due to resonance than alkoxide ion.   
                                                                                (or any other correct explanation) 
(ii) Because branching decreases the surface area / the van der Waals force decreases 
with a decrease in surface area. 
1 
 
1 
                                                       OR  
Br
|
CH
XII_39_043_56/1/1_Chemistry # Page-5 
 
 (b)  
(i)  
 
    
    
                                                                                               
                                                                                           (For any two correct steps) 
(ii)   
 /    
                     
½ + ½  
 
 
 
 
 
  
 
 
 
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24. (a) Aliphatic and aromatic primary amines on heating with chloroform and ethanolic 
potassium hydroxide form isocyanides or carbylamines which are foul-smelling 
substances.   /   
        
Isocyanide with an offensive smell is formed. 
                                                                                            (Explanation or reaction) 
(b) Phthalimide on treatment with ethanolic potassium hydroxide forms potassium 
salt of phthalimide which on heating with alkyl halide followed by alkaline 
hydrolysis produces the corresponding primary amine /   
 
                                                                                             (Explanation or reaction) 
 
1 
 
 
 
 
 
 
 
 
 
 
 
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