Preparing for the CBSE Class 12 Computer Science (083) board exam becomes much easier when students regularly practice CBSE Class 12 CS 083 previous year question papers with solutions 2024–25 (exam held on April 2, 2024). These papers help students clearly understand the latest exam pattern, marking scheme, and important topics such as Python programming, SQL queries, and data structures. By solving Class 12 Computer Science previous year board question papers with answers PDF, students get familiar with the types of questions frequently asked in exams, which improves their accuracy and conceptual clarity.
Moreover, practicing CBSE Class 12 CS solved previous year question papers for board exam preparation helps students manage time effectively and boosts their confidence before the final exam. It also allows them to identify weak areas and focus on improvement using reliable solutions. Regular practice of Class 12 CS 083 board exam sample papers and previous year questions with solutions ensures better performance, reduces exam stress, and increases the chances of scoring high marks in the CBSE board examination.
CBSE CLASS 12 COMPUTER SCIENCE (083) - SOLUTION
Class 12 CS (Code 083) - Previous Year Question Paper
(Session 2023-24)
Exam Date: April 2, 2024
Series &RQPS
Question Paper Code 91 Set 4
Question Paper Code 91 Set 4
Time allowed: 3 hours
Maximum Marks: 70
Maximum Marks: 70
General Instructions:
- This question paper contains 37 questions and five sections, Section A to E.
- All questions are compulsory.
- Section A have 21 questions carrying 1 mark each.
- Section B has 7 Very Short Answer type questions carrying 2 marks each.
- Section C has 3 Short Answer type questions carrying 3 marks each.
- Section D has 4 Long Answer type questions carrying 4 marks each.
- Section E has 2 questions carrying 5 marks each.
- All programming questions are to be answered using Python Language only.
- In case of MCQs, text of the correct answer should also be written.
SECTION A (21x1=21)
1. State True or False:
While defining a function in Python, the positional parameters in the function header must always be written after the default parameters.
Ans: False
2. The SELECT statement when combined with ____ clause, returns records without repetition.
a) DISTINCT
b) DESCRIBE
c) UNIQUE
d) NULL
3. What will be the output of the following statement:
print (165/42/5-8)
a) -3.33
b) 6.0
c) 0.0
d) -13.33
4. What possible output from the given options is expected to be displayed when the following Python code is executed ?
import random
Signal = ['RED', 'YELLOW', 'GREEN']
for K in range(2, 0, -1)
R = random. randrange (K)
print (Signal[R], end = '#')
a) YELLOW # RED #
b) RED # GREEN #
c) GREEN # RED #
d) YELLOW # GREEN #
5. In SQL, the aggregate function which will display the cardinality of the table is ____.
a) sum()
b) count (*)
c) avg()
d) sum(*)
6. Which protocol out of the following is used to send and receive emails over a computer network?
a) PPP
b) HTTP
c) FIP
d) SMTP (Simple Mail Transfer Protocol)
7. Identify the invalid Python statement from the following:
a) d = dict()
b) e = {}
c) f= []
d) g = dict{}
8. Consider the statements given below and then choose the correct output from the given options:
myStr="MISSISSIPPI"
print (myStr[:4]+"#"+myStr[-5:])
a) MISSI#SIPPI
b) MISS#SIPPI
c) MISS#IPPIS
d) MISSI#IPPIS
9. Identify the statement from the following which will raise an error:
a) print ("A"3)
b) print (53)
c) print("15" + 3)
d) print("15" + "13")
10. Select the correct output of the following code:
event="G20 Presidency@2023"
L=event.split(' ')
print (L[: :-2])
a) 'G20'
b) ['Presidency@2023']
c) ['G20']
d) 'Presidency@2023'
11. Which of the following options is the correct unit of measurement for network bandwidth?
a) KB
b) Bit
c) Hz
d) Km
12. Observe the given Python code carefully:
a=20
def convert (a):
b=20
a=a+b
convert (10)
print (a)
Select the correct output from the given options:
a) 10
b) 20
c) 30
d) Error
13. State whether the following statement is True or False:
While handling exceptions in Python, name of the exception has to be compulsorily added with except clause.
Ans: False
14. Which of the following is not a DDL command in SQL?
a) DROP
b) CREATE
c) UPDATE
d) ALTER
15. Fill in the blank:
____ is a set of rules that needs to be followed by the communicating parties in order to have a successful and reliable data communication over a network.
Ans: Protocol (or, name of any protocol)
16. Consider the following Python statement :
F=open ('CONTENT .TXT')
Which of the following is an invalid statement in Python?
a) F.seek(1,0)
b) F.seek(0,1)
c) F.seek(0,-1)
d) F.seek(0,2)
Q. 17 and 18 are ASSERTION (A) and REASONING (R) based questions. Mark the correct choice as
a) Both (A) and (R) are true and (R) is the correct. explanation for (A)
b) Both (A) and (R) are true and (R) is not the correct explanation for (A)
c) (A) is true but (R) is false
d) (A) is false but (R) is true
17. Assertion (A): CSV file is a human readable text file where each line has a number of fields, separated by comma or some other delimiter.
Reason (R): writerow() method is used to write a single row in a CSV file.
Ans: b) Both (A) and (R) are true and (R) is not the correct explanation for (A)
18. Assertion (A): The expression "HELLO".sort() in Python will give an error.
Reason (R): sort() does not exist as a method/function for strings in Python.
Ans: a) Both (A) and (R) are true and (R) is the correct. explanation for (A)
SECTION B (7x2=14)
19. (A) (i) Expand the following terms: XML, PPP
Ans: eXtensible Markup Language, Point to Point Protocol
(ii) Give one difference between circuit switching and packet switching.
Ans: Circuit Switching: Dedicated path is established between the centre and the receiver before starting data transmission. Entire data is transmitted in one go.
Packet Switching: Data to be transmitted is divided into small packets which are transmitted via nearest service provided till all packets reach the recipient where the packets are reassembled.
OR
(B) (i) Define the term web hosting.
Ans: Web hosting is a service that allows users to put a website or a web page on to the internet and make it a part of the world wide web.
(ii) Name any two web browsers.
Ans: Google Chrome, microsoft edge, safari, mozilla Firefox, netscape navigator, opera etc.
20. The code given below accepts five numbers and displays whether they are even or odd:
Observe the following code carefully and rewrite it after removing all syntax and logical errors:
Underline all the corrections made.
def EvenOdd ()
for i in range(5):
num=int (input ("Enter a number")
if num/2==0:
print ("Even")
else:
print ("Odd")
EvenOdd ()
Ans:
def EvenOdd () : #Error 1
for i in range(5):
num=int (input ("Enter a number")) #Error 2
if num%2==0: #Error 3
print ("Even")
else:
print ("Odd") #Error 4
EvenOdd ()
21 (A) Write a user defined function in Python named showGrades (S) which takes the dictionary S as an argument. The dictionary, S contains Name: [Eng,Math,Science] as key:value pairs. The function displays the corresponding grade obtained by the students according to the following grading rules:
| Average of Eng, Math, Science | Grade |
|---|---|
| >= 90 | A |
| < 90 but >= 60 | B |
| < 60 | C |
For example : Consider the following dictionary
S={"AMIT" : [92,86,64] ,"NAGMA": [65, 42,43] , "DAVID" : [92,90,88] }
The output should be:
AMIT - B
NAGMA - C
DAVID - A
Ans:
def showGrades (S) :
for K, V in S. items() :
if sum (V) / 3>=90 :
Grade="A"
elif sum (V) / 3>=60 :
Grade="A"
else :
Grade="C"
print (K, "-", Grade)
S={"AMIT" : [92,86,64],"NAGMA" : [65,42,43], "DAVID" : [92,90,88]}
showGrades (S)
OR
(B) Write a user defined function in Python named Puzzle (W,N) which takes the argument W as an English word and N as an integer and returns the string where every Nth alphabet of the word W is replaced with an underscore ("_").
For example : if W contains the word "TELEVISION" and N is 3, then the function should return the string "TE_EV_SI_N". Likewise for the word "TELEVISION" if N is 4, then the function should return
"TEL _VIS_ON".
Ans:
def Puzzle (W, N) :
W1=""
for i in range(len (W)) :
if (i+1)%N==0:
W1=W1+"_"
else :
W1=W1+W[i]
return W1
print (Puzzle ("TELEVISION",4))
22. Write the output displayed on execution of the following Python code:
LS=["HIMALAYA", "NILGIRI", "ALASKA", "ALPS"]
D={}
for S in LS :
if len(S)%4 == 0:
D[S] = len(S)
for K in D :
print(K,D[K], sep = "#")
Ans: HIMALAYA#8
ALPS#4
23. (A) Write the Python statement for each of the following tasks using built-in functions/methods only:
(i) To remove the item whose key is "NISHA" from a dictionary named Students.
For example, if the dictionary Students contains {"ANITA":90, "NISHA":76, "ASHA":92}, then after removal the dictionary should contain {"ANITA":90, "ASHA" : 92}
Ans: Students.pop("NISHA") OR del (Students ["NISHA"]) OR del Students ["NISHA"]
(ii) To display the number of occurrences of the substring "is" in a string named message.
For example if the string message contains "This is his book", then the output will be 3.
Ans: print (message.count("is")) OR message.count ("is")
OR
A tuple named subject stores the names of different subjects. Write the Python commands to convert the given tuple to a list and thereafter delete the last element of the list.
Ans: subject=list(subject)
subject.pop()
24. (A) Ms. Veda created a table named Sports in a MySQL database, containing columns Game_id, P_Age and G_name.
After creating the table, she realized that the attribute, Category has to be added. Help her to write a command to add the Category column. Thereafter, write the command to insert the following record in the table:
Game_id: G42
P_Age : Above 18
G_name : Chess
Category : Senior
Ans: ALTER TABLE SPORTS ADD COLUMN CATEGORY VARCHAR(10);
OR
(B) Write the SQL commands to perform the following tasks:
(i) View the list of tables in the database, Exam.
Ans: SHOW TABLES;
(ii) View the structure of the table, Term1.
Ans: DESCRIBE Term1; OR DESC Term1;
25. Predict the output of the following code:
def callon (b=20,a=10):
b=b+a
a=b-a
print (b,"#",a)
return b
x=100
y=200
x=callon (x,y)
print (x,"@",y)
y=callon (y)
print (x,"@",y)
Ans: 300#100
300@200
210#200
300@210
SECTION C (3x3=9)
26. Write the output on execution of the following Python code :
S="Racecar Car Radar"
L=S.split()
for W in L :
x=W.upper ()
if x==x[::-1]:
for I in x:
print (I,end="*")
else:
for I in W:
print (I,end="#")
print ()
Ans: R*A*C*E*C*A*R*
C#A#R#
R*A*D*A*R*
27. Consider the table ORDERS given below and write the output of the SQL queries that follow:
| ORDNO | ITEM | QTY | RATE | ORDATE |
|---|---|---|---|---|
| 1001 | RICE | 23 | 120 | 2023-09-10 |
| 1002 | PULSES | 13 | 120 | 2023-10-18 |
| 1003 | RICE | 25 | 110 | 2023-11-17 |
| 1004 | WHEAT | 28 | 65 | 2023-12-25 |
| 1005 | PULSES | 16 | 110 | 2024-01-15 |
| 1006 | WHEAT | 27 | 55 | 2024-04-15 |
| 1007 | WHEAT | 25 | 60 | 2024-04-30 |
(i) SELECT ITEM, SUM(QTY) FROM ORDERS GROUP BY ITEM;
| ITEM | SUM(QTY) |
|---|---|
| RICE | 48 |
| PULSES | 29 |
| WHEAT | 80 |
(ii) SELECT ITEM, QTY FROM ORDERS WHERE ORDATE BETWEEN '2023-11-01' AND '2023-12-31';
| ITEM | QTY |
|---|---|
| RICE | 25 |
| WHEAT | 28 |
(iii) SELECT ORDNO, ORDATE FROM ORDERS WHERE ITEM = 'WHEAT' AND RATE>=60;
| ORDNO | ORDATE |
|---|---|
| 1004 | 2023-12-25 |
| 1007 | 2024-04-30 |
28. (A) Write a user defined function in Python named showInLines () which reads contents of a text file named STORY.TXT and displays every sentence in a separate line.
Assume that a sentence ends with a full stop (.), a question mark (?), or an exclamation mark (!).
For example, if the content of file STORY. TXT is as follows:
Our parents told us that we must eat vegetables to be healthy. And it turns out, our parents were right! So, what else did our parents tell?
Then the function should display the file's content as follows:
Our parents told us that we must eat vegetables to be healthy.
And it turns out, our parents were right!
So, what else did our parents tell?
Ans:
def showInLines():
with open ("STORY.TXT", 'r') as F:
S = F.read()
for Win S:
if w =="." or W=="?" or W=="!":
print (W)
elif W=="\n":
print ( end ="")
else:
print (W, end="")
F.close()
OR
(B) Write a function, c_words()in Python that separately counts and displays the number of uppercase and lowercase alphabets in a text file, Words. txt.
Ans:
def c_words():
f=open ("Words.txt","r")
Txt=f.read()
CLower=CUpper=0
for i in Txt:
if i.islower():
CLower+=1
elif i.isupper():
CUpper+=1
print (CLower, CUpper)
f.close()
29. Consider the table Projects given below:
Table: Projects
| P_id | Pname | Language | Startdate | Enddate |
|---|---|---|---|---|
| P001 | School Management System | Python | 2023-01-12 | 2023-04-03 |
| P002 | Hotel Management System | C++ | 2022-12-01 | 2023-02-02 |
| P003 | Blood Bank | Python | 2023-02-11 | 2023-03-02 |
| P004 | Payroll Management System | Python | 2023-03-12 | 2023-06-02 |
Based on the given table, write SQL queries for the following:
(i) Add the constraint, primary key to column P_id in the existing table Projects.
Ans: ALTER TABLE Projects ADD PRIMARY KEY (P_id);
(ii) To change the language to Python of the project whose id is P002.
Ans: UPDATE Projects SET LANGUAGE="Python" WHERE P_id = "P002";
(iii) To delete the table Projects from MySQL database along with its data.
Ans: DROP TABLE Projects;
30. Consider a list named Nums which contains random integers.
Write the following user defined functions in Python and perform the specified operations on a stack named BigNums.
(i) PushBig(): It checks every number from the list Nums and pushes all such numbers which have 5 or more digits into the stack, BigNums.
(ii) PopBig(): It pops the numbers from the stack, BigNums and displays them. The function should also display "Stack Empty" when there are no more numbers left in the stack.
For example: If the list Nums contains the following data :
Nums = [213,10025,167,254923,14,1297653 , 31498 , 386, 92765]
Then on execution of PushBig(), the stack BigNums should store:
[10025, 254923, 1297653, 31498, 92765]
And on execution of PopBig() , the following output should be displayed:
92765
31498
1297653
254923
10025
Stack Empty
Ans:
def PushBig (Nums, BigNums):
for N in Nums:
if len(str(N)) >= 5:
BigNums.append(N)
def PopBig (BigNums):
while BigNums:
print (BigNums.pop())
else:
print("Stack Empty")
SECTION D (4x4=16)
31. Consider the tables Admin and Transport given below:
Table: Admin
| S_id | S_name | Address | S_type |
|---|---|---|---|
| S001 | Sandhya | Rohini | Day Boarder |
| S002 | Vedanshi | Rohtak | Day Scholar |
| S003 | Vibhu | Raj Nagar | NULL |
| S004 | Atharva | Rampur | Day Boarder |
Table: Transport
| S_id | Bus_no | Stop_name |
|---|---|---|
| S002 | TSS10 | Sarai Kale Khan |
| S004 | TSS12 | Sainik Vihar |
| S005 | TSS10 | Kamla Nagar |
Write SQL queries for the following:
(i) Display the student name and their stop name from the tables Admin and Transport.
Ans: SELECT S_name, Stop_name FROM Admin, Transport WHERE Admin.S_id = Transport.S_id;
(ii) Display the number of students whose S_type is not known.
Ans: SELECT COUNT(*) FROM Admin WHERE S_type IS NULL;
(iii) Display all details of the students whose name starts with 'V'.
Ans: SELECT * FROM Admin WHERE S_name LIKE 'v%';
(iv) Display student id and address in alphabetical order of student name, from the table Admin.
Ans: SELECT S_id, Address FROM Admi ORDER BY S_name;
32. Sangeeta is a Python programmer working in a computer hardware company. She has to maintain the records of the peripheral devices. She created a csv file named Peripheral.csv, to store the details. The structure of Peripheral .csv is:
[P_id, P_name, Price]
where
P_id is Peripheral device ID (integer)
P_name is Peripheral device name (String)
Price is Peripheral device price (integer)
Sangeeta wants to write the following user defined functions:
Add_Device(): to accept a record from the user and add it to a csv file, Peripheral.csv.
Count_Device(): To count and display number of peripheral devices whose price is less than 1000.
Ans:
import csv
def Add Device():
F = open ("Peripheral.csv", "a", newline='')
W = csv.writer (F)
P_id=int(input("Enter the Peripheral ID"))
P_name=input("Enter Peripheral Name")
Price=int(input("Enter Price"))
L= [P_id, P_name, Price]
W.writerow (L)
F.close()
def. Count Device():
F = open ("Peripheral.csv", "r")
L = list (csv.reader(F))
Count := 0
for D in L:
if int (D[2]) < 1000 :
Count+=1
print (Count)
F.close()
SECTION E (2x5=10)
33. Infotainment Ltd. is an event management company with its prime office located in Bengaluru. The company is planning to open its new division at three different locations in Chennai named as - Vajra, Trishula and Sudershana.
You, as a networking expert need to suggest solutions to the questions in part (i) to (v), keeping in mind the distances and other given parameters.
Distances between various locations:
| Vajra to Trishula | 350 m |
| Trishula to Sudershana | 415 m |
| Sudershana to Vajra | 300 m |
| Bengaluru Office to Chennai | 2000 km |
Number of computers installed at various locations:
| Vajra | 120 |
| Sudershana | 75 |
| Trishula | 65 |
| Bengaluru Office | 250 |
(i) Suggest and draw the cable layout to efficiently connect various locations in Chennai division for connecting the digital devices.
Ans:
(ii) Which block in Chennai division should host the server? Justify your answer.
Ans: Vajra can host the server as it has a maximum number of computers.
(iii) Which fast and effective wired transmission medium should be used to connect the prime office at Bengaluru with the Chennai division?
Ans: Optical Fiber
(iv) Which network device will be used to connect the digital devices within each location of Chennai division so that they may communicate with each other?
Ans: Switch / Hub / Router
(v) A considerable amount of data loss is noticed between different locations of the Chennai division, which are connected in the network. Suggest a networking device that should be installed to refresh the data and reduce the data loss during transmission to and from different locations of Chennai division.
Ans: Repeater
34. (A) (i) Differentiate between 'w' and 'a' file modesin Python.
Ans:
'w' Write Mode:
- Open the file in write mode.
- If the file doesn't exist, then a new file will be created.
- The file pointer is in the beginning of the file.
- If the file exists, the contents of the file, if any, are lost/truncated and the new data is added as fresh data into the file.
'a' Append Mode:
- Open the file in append mode.
- If the file doesn't exist, then a new file will be created.
- The file pointer is at the end of the file.
- If the file exists, the new data is added at the end of the file without deleting the previous contents of the file.
(ii) Consider a binary file, items.dat, containing records stored in the given format:
{item_id: [item_name, amount] }
Write a function, Copy_new(), that copies all records whose amount is greater than 1000 from items.dat to new_items.dat.
Ans:
import pickle
def Copy_new():
F2=open("new_items.dat", "wb")
try:
F1=open("items.dat","rb")
Datal-pickle.load(F1)
Data2={}
for K,V in Datal.items():
if V[1]>1000:
Data2 [K]=V
pickle.dump (Data2, F2)
F2.close()
except:
print("File not found!")
F1.close()
OR
(B) (i) What is the advantage of using with clause while opening a data file in Python ? Also give syntax of with clause.
Ans: The main advantage of using the with clause while opening a file in Python is that the file is automatically closed after the block of code is executed, even if an error occurs.
This makes the code safer, cleaner, and avoids memory/resource leaks.
Syntax of with clause:
with open(file_name, access_mode) as file_object:
# statements
Example:
with open("myfile.txt", "r+") as file_object:
content = file_object.read()
(ii) A binary file, EMP.DAT has the following structure:
[Emp Id, Name, Salary]
where
Emp _Id: Employee id
Name: Employee Name
Salary: Employee Salary
Write a user defined function, disp_Detail (), that would read the contents of the file EMP.DAT and display the details of those employees whose salary is below 25000.
Ans:
def disp_Detail ():
try:
with open ("EMP.DAT","rb") as F:
Data-pickle.load (F)
for D in Data:
if D [2]<25000:
print (D)
except:
print("File Not Found!!!")
35 (A) (i) Define cartesian product with respect to RDBMS.
Ans: Cartesian Product operation combines rows/tuples from two tables/relations. It results in all the pairs of rows from both the tables. It is denoted by 'X'.
(ii) Sunil wants to write a program in Python to update the quantity to 20 of the records whose item code is 111 in the table named shop in MySQL database named Keeper.
The table shop in MySQL contains the following attributes :
Item_code: Item code (Integer)
Item_name: Name of item (String)
Qty: Quantity of item (Integer)
Price: Price of item (Integer)
Consider the following to establish connectivity between Python and MySQL:
Username: admin
Password: Shopping
Host: localhost
Ans: import pymysql as pm
DB-pm.connect (host="localhost", user="admin", passwd="Shopping", database="Keeper")
MyCursor DB.cursor()
SQL=f"UPDATE SHOP SET QTY=%S WHERE ITEM CODE=%S"% (20,111)
#OR
SQL="UPDATE SHOP SET QTY-20 WHERE ITEM_CODE=111"
MyCursor.execute (SQL)
DB.commit()
OR
(B) (i) Give any two features of SQL.
Ans: (a) It is used to retrieve and view specific data from a table in a database.
(b) It decreases data duplicacy
(ii) Sumit wants to write a code in Python to display all the details of the passengers from the table flight in MySQL database, Travel. The table contains the following attributes:
F_code: Flight code (String)
F_name: Name of flight (String)
Source: Departure city of flight (String)
Destination: Destination city of flight (String)
Consider the following to establish connectivity between Python and MySQL :
Username: root
Password: airplane
Host: localhost
Ans:
import pymysql as pm
DB=pm.connect (host="localhost", user="root",\
password="airplane", database="Travel")
MyCursor DB.cursor()
MyCursor.execute ("SELECT * FROM Flight")
Rec=MyCursor.fetchall ()
for R in Rec:
print (R)
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