CBSE Sample Papers for Class 12 Computer Science Set 1 with Solutions

Students must start practicing the questions from CBSE Sample Papers for Class 12 Computer Science with Solutions Set 1 are designed as per the revised syllabus.

CBSE Sample Papers for Class 12 Computer Science Set 1 with Solutions

Time: 3 Hours
Maximum Marks: 70

General Instructions

1. This question paper contains 37 questions.
2. All questions are compulsory. However, internal choices have been provided in some questions. Attempt only one of the choices in such questions.
3. The paper is divided into 5 Sections – A, B, C, D and E.
4. Section A consists of 21 questions (1 to 21). Each question carries 1 Mark.
5. Section B consists of 7 questions (22 to 28). Each question carries 2 Marks.
6. Section C consists of 3 questions (29 to 31). Each question carries 3 Marks.
7. Section D consists of 4 questions (32 to 35). Each question carries 4 Marks.
8. Section E consists of 2 questions (36 to 37). Each question carries 5 Marks.
9. All programming questions are to be answered using Python Language only.
10. In the case of MCQ, the text of the correct answer should also be written.

Section A
(21 × 1 = 21)

Question 1.
State True or False:
The Python interpreter handles logical errors during code execution.
Answer:
False

Question 2.
Identify the output of the following code snippet:

text = "PYTHONPROGRAM"
text=text.replace('PY', '#')
print(text)

(a) #THONPROGRAM
(b) ##THON#ROGRAM
(c) #THON#ROGRAM
(d) #YTHON#ROGRAM
Answer:
(a) #THONPROGRAM

Question 3.
Which of the following expressions evaluates to False?
(a) not(True) and False
(b) True or False
(c) not(False and True)
(d) True and not(False)
Answer:
(a) not(True) and False

Question 4.
What is the output of the expression?

str='International'
Page: 2/10
print(str.split("n"))

(a) (‘I’, ‘ter’, ‘atio’, ‘al’)
(b) [‘I’, ‘ter’, ‘atio’, ‘al’]
(c) [‘I’, ‘n’, ‘ter’, ‘n’, ‘atio’, ‘n’, ‘al’]
(d) Error
Answer:
(b) [‘I’, ‘ter’, ‘atio’, ‘al’]

Question 5.
What will be the output of the following code snippet?

str= "World Peace"
print(str[-2::-2])

Answer:
ce lo

Question 6.
What will be the output of the following code?

tuple1 = (1, 2, 3)
tuple2 = tuple1
tuple1+= (4,)
print(tuple1 == tuple2)

(a) True
(b) False
(c) tuple1
(d) Error
Answer:
(b) False

Question 7.
If my_dict is a dictionary as defined below, then which of the following statements will raise an exception?

my_dict = {'apple': 10, 'banana': 20, 'orange': 30}
(a) my_dict.get('orange')
(b) print(my_dict['apple', 'banana'])
(c) my_dict['apple']=20
(d) print(str(my_dict))

Answer:

(b) print(my_dict['apple', 'banana'])

Question 8.
What does the list.remove(x) method do in Python?
(a) Removes the element at index x from the list
(b) Removes the first occurrence of value x from the list
(c) Removes all occurrences of value x from the list
(d) Removes the last occurrence of value x from the list
Answer:
(b) Removes the first occurrence of value x from the list

Question 9.
Which of the following statements will cause an error?
(a) t=1,
(b) t=(1,)
(c) t=(1)
(d) t=tuple(1)
Answer:
(d) t=tuple(1)

Question 10.
Write the missing statement to complete the following code:

file = open("example.txt", "r")
data = file.read(100)
_______________#Move the file pointer to the beginning of the file
next_data = file.read(50)
file.close()

Answer:
file.seek(0)

Question 11.
State whether the following statement is True or False:
The final block in Python is executed only if no exception occurs in the try block.
Answer:
False

Question 12.
What will be the output of the following code?

c = 10
def add():
global c
c = c + 2
print(c,end='#')
add()
c=15
print(c,end='%')

(a) 12%15#
(b) 15#12%
(c) 12#15%
(d) 12%15#
Answer:
(c) 12#15%

Question 13.
Which SQL command can change the degree of an existing relation?
Answer:
Alter table command

Question 14.
What will be the output of the query?
SELECT * FROM products WHERE product_name LIKE ‘App%’;
(a) Details of all products whose names start with ‘App’
(b) Details of all products whose names end with ‘App’
(c) Names of all products whose names start with App’
(d) Names of all products whose names end with ‘App’
Answer:
(a) Details of all products whose names start with ‘App’

Question 15.
In which datatype the value stored is padded with spaces to fit the specified length.
(a) DATE
(b) VARCHAR
(c) FLOAT
(d) CHAR
Answer:
(d) CHAR

Question 16.
Which aggregate function can be used to find the cardinality of a table?
(a) sum()
(b) count()
(c) avg()
(d) max()
Answer:
(b) count()

Question 17.
Which protocol is used to transfer files over the Internet?
(a) HTTP
(b) FTP
(c) PPP
(d) HTTPS
Answer:
(b) FTP

Question 18.
Which network device is used to connect two networks that use different protocols?
(a) Modem
(b) Gateway
(c) Switch
(d) Repeater
Answer:
(b) Gateway

Question 19.
Which switching technique breaks data into smaller packets for transmission, allowing multiple packets to share the same network resources.
Answer:
Packet switching

Directions (Q. 20 and 21) are Assertion (A) and Reason (R) based questions. Mark the correct choice as
(a) Both A and R are true and R is a correct explanation of A.
(b) Both A and R are true but R is not a correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.

Question 20.
Assertion (A): In the case of positional arguments, the function call and function definition statements match in terms of the number and order of arguments.
Reason (R): During a function call, positional arguments should precede keyword arguments in the argument list.
Answer:
(b) For positional arguments there should be an exact match between the actual and formal parameters in order and number. Also, positional arguments should precede keyword arguments in the argument list.
Hence, both A and R are true and R is not the correct explanation for A.

Question 21.
Assertion (A): A SELECT command in SQL can have WHERE and HAVING clauses.
Reason (R): WHERE and HAVING clauses are used to check conditions, therefore, these can be used interchangeably.
Answer:
(c) WHERE is used for matching single rows and having filter groups, so both can be used in a single query, but their purposes are different. Hence, A is True but R is False.

Section B
(7 × 2 = 14)

Question 22.
How is a mutable object different from an immutable object in Python?
Identify one mutable object and one immutable object from the following:
(1,2), [1,2], {1:1,2:2}, ‘123’
Answer:
An object that can be changed is mutable. While an object that cannot be changed after its creation is immutable.
Mutable object: [1,2] or {1:1,2:2} (Anyone)
Immutable object: (1,2) or ‘123’ (Anyone)

Question 23.
Give two examples of each of the following:
(I) Arithmetic operators
(II) Relational operators
Answer:
(I) Arithmetic operators ** Exponentiation, % Modulus or Remainder.
(II) Relational operators > Greater than, = Equality.

Question 24.
If L1=[1,2,3,2,1,2,4,2,…], and L2=[10,20,30,…], then
(I) (A) Write a statement to count the occurrences of 4 in L1.
Or
(B) Write a statement to sort the elements of list L1 in ascending order.
(II) (A) Write a statement to insert all the elements of L2 at the end of L1.
Or
(B) Write a statement to reverse the elements of list L2.
Answer:
(I) (A) L1.count(4) Or (B) L1.sort()
(II) (A) L1.extend(1,2) Or (B) L2.reverse()

Question 25.
Identify the correct output(s) of the following code. Also, write the minimum and the maximum possible values of the variable b.

import random
a="Wisdom"
b=random.randint(1,6)
for i in range(0,b,2):
print(a[i],end='#')

(a) W#
(b) W#i#
(c) W#s#
(d) W#i#s#
Answer:
The randint() function will return values from 1 to 6.
Permissible values for the loop variable i are 0, 2, 4.
Hence the outputs can be options (a) or (c).

Question 26.
Give an example of a table that has one Primary key and two alternate keys. How many Candidate keys will this table have?
Answer:
Table : Emp (EmpId , Ename , Adhar, VoterId, Dept)
Number of candidate keys : 3
Here EmpId can act as the Primary key and Adhar, VoterId can act as an alternate key.
All the fields of a table that can act as primary keys are candidate keys.
Here EmpId, adhar, and voterid, all can become the primary key.

Question 27.
(I) (A) What constraint should be applied on a table column so that duplicate values are not allowed in that column, but NULL is allowed?
Or
(B) What constraint should be applied on a table column so that NULL is not allowed in that column, but duplicate values are allowed?
(II) (A) Write an SQL command to remove the Primary Key constraint from a table, named MOBILE. M_ID is the primary key of the table.
Or
(B) Write an SQL command to make the column M_ID the Primary Key of an already existing table, named MOBILE.
Answer:
(I) (A) UNIQUE: The Unique constraint does not allow duplicate values but allows NULL values.
Or
(B) NOT NULL: The NOT NULL constraint does not allow NULL values but allows duplicate values.
(II) (A) Alter table MOBILE Drop Primary key(M_ID);
Or
(B) Alter table MOBILE ADD Primary key(M_ID);

Question 28.
(A) List one advantage and one disadvantage of star topology.
Or
(B) Expand the term SMTP. What is the use of SMTP?
Answer:
(A) Advantage of star topology: Error detection and isolation is easy.
Disadvantage of star topology: Costly due to independent cables.
Or
(B) SMTP: Simple mail transfer protocol.
SMTP is a common language used to send email. It’s a universal set of rules that allow servers and email clients to communicate via the internet. Think of SMTP as the language your computer uses to tell a server where an email goes, what’s in the email, what’s attached, and more.

Section C
(3 × 3 = 9)

Question 29.
(A) Write a Python function that displays all the words containing @cmail from a text file “Emails.txt”.
Or
(B) Write a Python function that finds and displays all the words longer than 5 characters from a text file “Words.txt”.
Answer:

(A) def show():
f=open("Email.txt", 'r')
data=f.read()
words=data.split(' ')
for word in words:
if '@cmail' in word:
print(word.end=' ')
f.closed()
Or
(B) def display_long_words():
with open("Words.txt", 'r') as file:
data=file.read()
words=data.split()
for word in words:
if len(word)>5:
print(word,end=' ')

Question 30.
(A) You have a stack named BooksStack that contains records of books. Each book record is represented as a list containing book_title, author_name, and publication_year.
Write the following user-defined functions in Python to perform the specified operations on the stack BooksStack:
(I) push_book(BooksStack, new_book): This function takes the stack BooksStack and a new book record new_book as arguments and pushes the new book record onto the stack.
(II) pop_book(BooksStack): This function pops the topmost book record from the stack and returns it. If the stack is already empty, the function should display “Underflow”.
(III) peep(BookStack): This function displays the topmost element of the stack without deleting it. If the stack is empty, the function should display ‘None’.
Or
(B) Write a Python program to input an integer and display all its prime factors in descending order, using a stack. For example, if the input number is 2100, the output should be: 7 5 5 3 2 2 (because prime factorization of 2100 is 7×5×5×3×2×2)
Hint: The smallest factor, other than 1, of any integer, is guaranteed to be prime.
Answer:
(A) (I) def push_book(BooksStack, new_book):
BooksStack.append(new_book)
Here the stack is implemented using a stack.
Hence the append() function is used to add the new element at the top of the stack.

(II) def pop_book(BooksStack):
if not BooksStack:
print("Underflow")
else:
return(BookStack.pop())

Here the stack is implemented using a stack.
The pop() function removes and displays the last element of a list.
Hence the pop() function is used here to take out the topmost element of the stack.

(III) def peep(BooksStack):
if not BooksStack:
print("None")
else:
print(BookStack[-1])

Since the topmost element has to be displayed without removing it, the pop() function cannot be used here.
Instead, the BookStack[-1] statement prints the last element of the list that has index -1.
Or

(B) n=int(input("Enter an integer: "))
s=[] #stack
f=2
while n>1:
if n%f==0:
s.append(f)
n//=f
else: f+=1
while s:
print(s.pop(),end=' ')

To find the prime factorization the number is repeatedly divided to find the clear division, starting from f=2. When no longer divisible by 2 it is divided by the next prime factor and so on. All such factors are pushed into the stack. Finally, the stack contents are popped.

Question 31.
Consider the table ORDERS as given below, and write the following queries:

Note: The table contains many more records than shown here.
(A) (I) To display the total Quantity for each Product, excluding Products with a total Quantity of less than 5.
(II) To display the orders table sorted by total price in descending order.
(III) To display the distinct customer names from the Orders table.
Or
(B) (I) To display the total number of orders quantity-wise.
(II) To delete all the orders where the Product is a Laptop.
(III) Display the sum of the Price of all the orders for which the quantity is null.
Answer:

(A) (I) select Product, sum(Quantity) from orders group by product having sum(Quantity)>=5;
(I) select * from orders order by Price desc;
(III) select distinct C_Name from orders;
Or
(B) (I) Select quantity, count(*) from orders group by quantity;
(II) Delete from orders where product = "Laptop";
(III) Select sum(price) from orders where quantity is null;

Section D
(4 × 4 = 16)

Question 32.
(A) I. When is the ZeroDivisionError exception raised in Python?
II. Give an example code to handle ZeroDivisionError. The code should display the message “Division by Zero is not allowed” in case of a ZeroDivisionError exception, and the message “Some error occurred” in case of any other exception.
Or
(B) I. When is the NameError exception raised in Python?
II. Give an example code to handle NameError. Hie code should display the message “Some name is not defined” in case of a NameError exception, and the message “Some error occurred” in case of any other exception.
Answer:
(A) (I) ZeroDivisionError exception is raised whenever a number is divided by zero.

(II) try:
a=int(input("Enter the numerator: "))
b=int(input("Enter the denominator: "))
print("Division is : ", a/b)
except ZeroDivisionError:
print("Division by Zero is not allowed")
except:
print("Some other Error Occurred")

Or
(B) (I) NameError is raised when the identifier being accessed is not defined in the local or global scope.

(II) try:
p=input("Enter a word : ")
print("Replica :” , q*3)
except NameError:
print("Some name is not defined")
except:
print("Some Error Occurred")

Question 33.
A csv file “Happiness.csv” contains the data of a survey. Each record of the file contains the following data:

• Name of a country
• Population of the country
• Sample Size (Number of persons who participated in the survey in that country)
• Happy (Number of persons who accepted that they were Happy)

For example, a sample record of the file may be:
Signiland, 5673000, 5000, 3426
Write the following Python functions to perform the specified operations on this file:
(I) Read all the data from the file and display all those records for which the population is more than 5000000.
(II) Count the number of records in the file.
Answer:

(I) import csv
def show():
f=open("happiness.csv".'r')
records=csv.reader(f)
next(records. None) #To skip the Header row
for i in records:
if int(i[1])>5000000:
print(i)
f.close()
(II) import csv
def Count_records():
f=open("happiness.csv",'r')
records=csv.reader(f)
next(records, None) #To skip the Header row
count=0
for i in records:
count+=1
print(count)
f.close()

Question 34.
Saman has been entrusted with the management of Law University Database. He needs to access some information from FACULTY and COURSES tables for a survey analysis. Help him extract the following information by writing the desired SQL queries as mentioned below.

(I) To display complete details (from both the tables) of those Faculties whose salary is less than 12000.
(II) To display the details of courses whose fees is in the range of 20000 to 50000 (both values included).
(III) To increase the fees of all courses by 500 which have “Computer” in their Course names.
(IV) (A) To display names (FName and LName) of faculty taking System Design.
OR
(B) To display the Cartesian Product of these two tables.
Answer:

(I) Select * from Faculty A, Courses B
where A.F_ID= B.F_ID and A. Salary <12000;
(II) Select * from Courses where Fees are between 20000 and 50000;
(III) Update Courses set Fees =Fees + 500 where Cname like “%Computer%”;
(IV) (A) Select A.Fname, A.Lname from Faculty A, Courses B where A.F_ID= B.F_ID and B.CName=“System Design”;

Or
(B) Select * from Faculty, Courses;

Question 35.
A table, named STATIONERY, in the ITEMDB database, has the following structure:

Write the following Python function to perform the specified operation:
AddAndDisplay(): To input details of an item and store it in the table STATIONERY. The function should then retrieve and display all records from the STATIONERY table where the Price is greater than 120. Assume the following for Python-Database connectivity:
Host: localhost, User: root, Password: Pencil
Answer:

import mysql.connector as mycon def Add_Item():
mycon=mycon. connect(host="local host", user="root",
passwd="Pencil",database="ITEMDB")
mycur= mycon.cursor()
itmno=input("Enter Item Number: ")
itmnm=input("Enter Item Name: ")
itmpr=input("Enter price: ")
itmqty=input("Enter qty: ")
query="Insert into stationer y values ({}, {}, {}, {})"
query=query.format(itmno, itmnm, itmpr, itmqty)
mycur.execute(query)
mycon.commit()
mycur.execute("select * from stationery where price>120")
for rec in mycur:
print(rec)
mycon.close()

Section E
(2 × 5 = 10)

Question 36.
Surya is a manager working in a recruitment agency. He needs to manage the records of various candidates. For this he wants the following information of each candidate to be stored:
Candidate_ID – integer
Candidate_Name – string
Designation – string
Experience – float
You, as a programmer of the company, have been assigned to do this job for Surya.
Suggest:
(I) What type of file (text file, csv file, or binary file) will you use to store this data? Give one valid reason to support your answer.
(II) Write a function to input the data of a candidate and append it in the file that you suggested in part (I) of this question.
(III) Write a function to read the data from the file that you suggested in part (I) of this question and display the data of all those candidates whose experience is more than 10.
Answer:

(I) csv file. Csv files store data in a simple format exchangeable across different platforms
(II) import csv
def add_data():
with open("Candidates.csv",'a') as f:
cwriter = csv. writer(f)
cid=input("Enter Candidate ID: ")
cnm=input("Enter Candidate name: ")
cdg=input("Enter Designation: ")
cexp=input("Enter Experience: ")
rec=[cid,cnm,cdg.cexp]
cwriter.writerow(rec)
(III) import csv
with open('Candidates.csv', 'r’) as file:
csvFile = csv.reader(file)
for rec in csvFile:
if int(rec[3])>10:
print (rec)

Question 37.
Event Horizon Enterprises is an event planning organization. It is planning to set up its India campus in Mumbai with its head office in Delhi. The Mumbai campus will have four blocks/buildings – ADMIN, FOOD, MEDIA, and DECORATORS. You, as a network expert, need to suggest the best network-related solutions for them to resolve the issues/problems mentioned in points (I) to (V), keeping in mind the distances between various blocks/buildings and other given parameters.


Distance of Delhi Head Office from Mumbai Campus = 1500 km
Number of computers in each of the blocks/Center is as follows:

(I) Suggest the most appropriate location of the server inside the MUMBAI campus. Justify your choice.
(II) Which hardware device will you suggest to connect all the computers within each building?
(III) Draw the cable layout to efficiently connect various buildings within the MUMBAI campus. Which cable would you suggest for the most efficient data transfer over the network?
(IV) Is there a requirement of a repeater in the given cable layout? Why/Why not?
(V) (A) What would be your recommendation for enabling live visual communication between the Admin Office at the Mumbai campus and the DELHI Head Office from the following options:
(a) Video Conferencing
(b) Email
(c) Telephony
(d) Instant Messaging
Or
(B) What type of network (PAN, LAN, MAN, or WAN) will be set up among the computers connected in the MUMBAI campus?
Answer:
(I) MEDIA: As it houses the maximum number of computers.
(II) Switch: A Switch is an intelligent device that can connect multiple nodes.
(III) Cable layout

Optical fibre cable should be used
(IV) Yes, between MEDIA and Admin as the distance is 96m.
(V) (A) Video conferencing
Or
(B) LAN