CBSE Class 12 Sample Paper 2024 Solution for Computer Science

Central Board of Secondary Education

SAMPLE PAPER
Class 12
2024

Solutions

Marking Scheme

Class XII

Computer Science (083)

Time Allowed: 3 hours MM: 70

Ques Question and Answers Distribution Total
No of Marks Marks

SECTION A
1 False 1 mark for 1
answer

2 Option b 1 mark for 1
6,20
answer

3 Option c 1 mark for 1
-244.0 answer

4 PYTHON-is-Fun 1 mark for 1
answer

5 Option b 1 mark for 1
8,15
answer

6 Option a 1 mark for 1
PAN
answer

7 Option b 1 mark for 1
del D1["Red"] answer

8 Option b 1 mark for 1
answer

[1]

ceieP0

9 Option d 1 mark for 1
Statement 4 answer

10 Option b 1 mark for 1
YELLOW* answer

WHITE*
BLACK*
RED*

11 Option b 1 mark for 1
Modulator answer

12 Option c 1 mark for 1
global b answer

13 True 1 mark for 1
answer

14 Option c 1 mark for 1
A candidate key that is not a primary key is a foreign key. answer

15 circuit 1 mark for 1
answer

16 Option c 1 mark for 1
seek() answer

[2]

17 Option d 1 mark for 1
A is false but R is True correct
answer

18 Option b 1 mark for 1
Both A and R are true but R is not the correct explanation for A answer

SECTION B
19 (i) ½ mark for 1+1=2
each correct
POP3 – Post Office Protocol 3 expansion

URL – Uniform Resource Locator

(ii)

HTML( Hyper text mark Up language)

 We use pre-defined tags
 Static web development language – only focuses on how
data looks
 It use for only displaying data, cannot transport data
 Not case sensistive

XML (Extensible Markup Language) 1 mark for
any one
 we can define our own tags and use them
difference
 Dynamic web development language – as it is used for
No mark to
transporting and storing data be awarded if
 Case sensitive only full form
is given

20 def revNumber(num): ½ mark for 2
rev = 0 each
rem = 0
while num > 0:
[3]

rem =num %10 correction
rev = rev*10 + rem made
num = num//10
return rev
print(revNumber(1234))

21 ½ mark for 2
function
header

correct loop

correct if
statement

displaying
OR
the output

function
header

using split()

adding to
tuple
Note: Any other correct logic may be marked ½ mark for
return
statement

[4]

22 4*L ½ mark for 2
each correct
33*4
line of output
21*S
10*6
23 (i) L1.insert(2,200) 1 mark for 1+1=2
each correct
(ii) message.endswith('.') statement

24 SQL Command to add primary key: 1 mark for 2
ALTER TABLE Employee ADD EmpId INTEGER ALTER TABLE
command
PRIMARY KEY;

As the primary key is added as the last field, the command for
1 mark for
inserting data will be: correct
INSERT
INSERT INTO Employee command
VALUES("Shweta","Production",26900,999);
OR
INSERT INTO
Employee(EmpId,Ename,Department,Salary)
VALUES(999,"Shweta","Production",26900);
25 10.0$20 1 mark for 2
each correct
10.0$2.0###
line of output

SECTION C
26 ND-*34 ½ mark for 3
each correct
character

27

[5]

1 mark for 1*3=3
each correct
(i)
output
COUNT(DISTINCT SPORTS)
4

(ii)
CNAME SPORTS
AMINA CHESS

(iii)
CNAME AGE PAY
AMRIT 28 1000
VIRAT 35 1050

28 1 mark for 3
correctly
opening and
closing files

correctly
reading data

1 mark for
correct loop
and if
statement
OR
displaying
data

[6]

1 mark for
correctly
opening and
closing the
files

correctly
reading data

1 mark for
correct loop
and if
statement
Note: Any other correct logic may be marked
displaying
the output.

29 (i) 1 mark for 1*3=3
each correct
UPDATE Personal
query
SET Salary=Salary*0.5
WHERE Allowance IS NOT NULL;

(ii)
SELECT Name, Salary+Allowance AS
"Total Salary" FROM Personal;

(iii)
DELETE FROM Personal
WHERE Salary>25000

[7]

30 1 ½ marks for 3
each function

SECTION D
31 a) 1 mark for 1*5=5
each correct
Bus Topology
answer
ENGINEERING
Admin

BUSINESS
MEDIA

b) Switch
c) Admin block, as it has maximum number of computers.
d) Microwave
e) Firewall
32 (i) 1 mark for 2+3=5
each correct
r+ mode:
difference
 Primary function is reading
( minimum
 File pointer is at beginning of file two
differences
 if the file does not exist, it results in an error
should be
w+ mode: given)

[8]

 primary function is writing
 if the file does not exist, it creates a new file.
 If the file exists, previous data is overwritten
 File pointer is at the beginning of file
(ii) ½ mark for
correctly
opening and
closing files

correct try
and except
block

correct loop

1 mark for
correctly
copying data

return
statement
OR
(Only for option ii)
correctly
opening and
closing files

correct try
and except
block

correct loop

[9]

correct if
statement
Note: Any other correct logic may be marked
1 mark for
correctly
displaying
data

33 (i) Domain is a set of values from which an attribute can ½ mark for 1+4=5
take value in each row. For example, roll no field can
definition
have only integer values and so its domain is a set of
integer values correct
example

(ii) ½ mark for
importing
module

1 mark for
connect()

correctly
accepting the
input

1 ½ mark for
Note: Any other correct logic may be marked correctly
executing the
query

correctly
using
commit()

[10]

SECTION E
34 (i) 1 mark for 1*4=4
each correct
SELECT PName, BName FROM PRODUCT P,
query
BRAND B WHERE P.BID=B.BID;
(ii)
DESC PRODUCT;
(iii)
SELECT BName, AVG(Rating) FROM PRODUCT
P, BRAND B
WHERE P.BID=B.BID
GROUP BY BName
HAVING BName='Medimix' OR
BName='Dove';
(iv)
SELECT PName, UPrice, Rating
FROM PRODUCT
ORDER BY Rating DESC;
35 ½ mark for 4
accepting
data
correctly

opening and
closing file

writing
headings

writing row

[11]

opening and
closing file

reader object

print heading

printing data

[12]