CBSE Sample Papers for Class 12 Computer Science Set 4 with Solutions

Students must start practicing the questions from CBSE Sample Papers for Class 12 Computer Science with Solutions Set 4 are designed as per the revised syllabus.

CBSE Sample Papers for Class 12 Computer Science Set 4 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 remove() method removes the element at the index specified”
Answer:
False

Question 2.
What will be the output for the following Python statements?

D=("AMIT":90, "RESHMA":96. "SUKHBIR":92. "JOHN":95)
print("JOHN" in D, 90 in D, sep = "#")

(a) True#False
(b) True#True
(c) False#True
(d) False#False
Answer:
(a) True#False

Question 3.
Which of the following will result in True?

(a) math.pow(2,3) + math.sqrt(121) > 12
(b) math.ceil(19.22) + math.floor(15.99) > 34
(c) math.sqrt(100//10-6 )== 5
(d) math.pow(2,5) + 56//2 > 70

Answer:

(b) math.ceil(19.22) + math.floor(15.99) > 34

Question 4.
Let list1 = [3, 4, 5, 20, 5, 25, 1, 3], what is list1 after list1.pop(1)?
(a) [3, 4, 5, 20, 5, 25, 1, 3]
(b) [1, 3, 3, 4, 5, 5, 20, 25]
(c) [3, 5, 20, 5, 25, 1, 3]
(d) [1, 3, 4, 5, 20, 5, 25]
Answer:
(c) [3, 5, 20, 5, 25, 1, 3]

Question 5.
The output of the code will be:

S="Wonders of World"
print(s.count(‘o’) + s.index('o')

(a) 3
(b) 4
(c) 2
(d) 1
Answer:
(b) 4

Question 6.
a=1.0
b=1.0
a is b # Line 1

The output of Line 1 will be
(a) False
(b) True
(c) 1.0
(d) 0.0
Answer:
(b) True

Question 7.

def add(a, b):
return a+5, b+5
result = add(3, 2)
print(result)

(a) 15
(b) 8
(c) (8, 7)
(d) Syntax Error
Answer:
(c) (8, 7)

Question 8.
Which of the following is not a keyword?
(a) eval
(b) assert
(c) nonlocal
(d) pass
Answer:
(a) eval

Question 9.
What will the following code display?

S=173
P=173
S>=P

(a) True
(b) False
(c) Cannot predict
(d) Error
Answer:
(a) True

Question 10.
Fill in the missing blank in the code given to read the contents of the csv file and display

import csv
fcsv=open(“games.csv”,"r")
csvro =csv.reader(fcsv)
for_____________:
print(rec)
fcsv.close()

Answer:
rec in csvro:

Question 11.
State True or False:
The object must be created of a specific class of which the error has occurred otherwise runtime error will occur.
Answer:
False

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

def goodmorning():
S = "GOOD MORNING"
print (S.capitalize(), S.title ( ), end="!”)

(a) GOOD MORNING! Good morning
(b) Good Morning! Good morning
(c) Good morning! Good morning!
(d) Good morning Good Morning!
Answer:
(d) Good morning Good Morning!

Question 13.
Which of the following is the correct syntax to add a column in an SQL command?

(a) ALTER TABLE table_name ADD column_name data_type;
(b) ALTER TABLE ADD column_name data_type;
(c) ALTER table_name ADD column_name data_type;
(d) None of the above

Answer:

(a) ALTER TABLE table_name ADD column_name data_type;

Question 14.
What will the following query do?

Alter table Teacher Modify Tname varchar(50) NOT NOLL:

(a) Adds a new column Tname.
(b) Modifies the column Tname to varchar(50) only.
(c) Modifies the column Tname to varchar(50) and adds the NOT NULL constraint to it
(d) None of the above
Answer:
(c) Modifies the column Tname to varchar(50) and adds the NOT NULL constraint to it

Question 15.
Which of the following kinds of join do not have a joining condition?
(a) Cross join
(b) Non equi join
(c) Equi join
(d) None have a joining condition.
Answer:
(a) Cross join

Question 16.
The clause that uses % and _ characters for matching patterns in a query is:
(a) Between
(b) Order by
(c) Pattern
(d) Like
Answer:
(d) Like

Question 17.
________________ protocol is used to send mail.
(a) SMTP
(b) FTP
(c) POP
(d) HTTPS
Answer:
(a) SMTP

Question 18.
What is the expanded form of XML?
(a) Extended Markup Language
(b) Extensible Markup Language
(c) Extra Markup Language
(d) None of these
Answer:
(b) Extensible Markup Language

Question 19.
Which type of transmission sends data to all devices in a network segment, with only the intended recipient accepting the data?
Answer:
Broadcast transmission

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): A Python function can return more than one value to the calling function.
Reason (R): The return statement takes only a list as a parameter.
Answer:
(c) A is true and R is false.

Question 21.
Assertion (A): A foreign key is an attribute whose value is derived from the primary key of another relation.
Reason (R): A foreign key is used to represent the relationship between two relations.
Answer:
(a) Both A and R are true and R is a correct explanation of A.

Section B
(7 × 2 = 14)

Question 22.
Define the following terms.
(i) Comments
(ii) Variables
(iii) Data type
Answer:
(i) Comments: A hash sign (#) that is not inside a string begins a single-line comment. We can use triple quoted string for giving multi-line comments.
(ii) Variables: A variable in Python is defined through assignment. There is no concept of declaring a variable outside of that assignment.
(iii) Data type: It is a set of values and the allowable operations on those values. Python has a great set of useful data types.

Question 23.
(a) Give examples of: Two programming constructs in Python.
(b) What will range(-5, -10) return?
Answer:
(a) if or if…else or if…elif….else
(b) [] empty set

Question 24.
Write Python statements to achieve the following tasks using built-in functions only:
(I) (a) To convert a fractional number into a whole as the nearest next.
Or
(b) To get the position of an item it in a list L.
Or
(II) Write a Python function sum_of_squares that takes a list of integers as input and returns the sum of the squares of all the elements in the list.
Answer:
(I) (a) math.round(5.8)
Or
(b) L.index(it1)
Or

(II) def sum_of_squares(lst):
total = 0
for num in lst:
total += num ** 2
return total
example_list = [1, 2, 3, 4]
result = sum_of_squares (example_list)
print(result)

Question 25.
What possible outputs(s) are expected to be displayed on screen at the time of execution of the program from the following code? Select which option/s is/are correct.

import random
print(random.randint(15,25), end = ' ')
print((100) + random.randint(15,25), end = ' ')
print((100) - random.randint(15,25), end = ' ')
print((100) * random.randint(15,25))

(a) 15 122 84 2500
(b) 21 120 76 1500
(c) 105 107 105 1800
(d) 110 105 105 1900
Answer:
(b) 21 120 76 1500

Question 26.
Differentiate between the cardinality and the degree of a table with the help of an example.
Answer:
Cardinality is defined as the number of rows in a table.
The degree is the number of columns in a table.
e.g. consider the following table:

Cardinality: 3
Degree: 2

Question 27.
(I) Write commands/clauses/functions to be used for the following:
(a) Write an SQL query to add a column total_price with data type numeric and size 10,2 in a table Product.
Or
(b) Why is the varchar data type preferred over char?
Or
(II) (a) Sonal needs to display the names of teachers, who have “0” as the third character in their name. She wrote the following query.
SELECT NAME FROM TEACHER WHERE NAME LIKE ‘_%0%’
However, the query is not producing the result. Identify the problem
Or
(b) Which mySQL function rounds a number to certain decimal places?
Answer:

(I) (a) ALTER TABLE Product ADD total_price NUMERIC(10, 2);

Or
(b) varchar is more flexible than char. It is variable length and saves memory rather than, char which is fixed length and wastes memory.
(II) (a) The wildcards are incorrect. The corrected query is

SELECT NAME FROM TEACHER WHERE NAME LIKE '-%0%';

Or
(b) round() function

Question 28.
(a) Give one suitable example of each URL and domain name.
(b) How is a crossover Ethernet cable different from the rest of the Ethernet cables?
Or
(a) Which wireless technology is commonly used in mobile phones?
(b) Which type of network (out of LAN, PAN, and MAN) is formed, when you connect two mobiles using Bluetooth to transfer a picture file?
Answer:
(a) URL: http://www.gabsclasses.com/aboutus
Domain name: www.gabsclasses.com
(b) A crossover cable is a special type of Ethernet cable specially designed for connecting two computers, whereas most Ethernet cables are designed to connect one computer to a router or a switch.
Or
(a) Bluetooth is commonly used as a wireless technology in mobile phones and laptops.
(b) When two mobiles are connected using Bluetooth to transfer a picture file, a PAN (Personal Area Network) is created.

Section C
(3 × 3 = 9)

Question 29.
Define a function in Python to accept a sentence and count the number of occurrences of the word “is” and “was”.
Example:
Input: “He is a good boy. She was and is a good girl”
Output:
No. of is: 2
No. of was: 1
Or
Write a definition of a function that takes input from a sentence and displays the list of words that start with a lowercase vowel and the list of words that start with an uppercase vowel separately.
Example
Input: A quick black elephant enters Into a jungle.
Output
List of words starting with lowercase vowels [elephant’, ‘enters’, ‘a’]
List of words starting with uppercase vowels [‘A’, ‘Into’]
Answer:

def counts(s):
iscount=0
wascount=0
for w in s.split(' '):
if w=="is":
iscount+=1
elif w=="was":
wascount+=1
print("No. of is :”,iscount)
print("No. of was :",wascount)
def main():
counts("He is a good boy. She was and is a good girl")
main()
Or
def counts(s):
L1=[ ]
L2=[ ]
for w in s.split(' '):
if w[0] in 'aeiou':
L1.append(w)
elif w[0] in 'AEIOU':
L2.append(w)
print("List of words starting with lowercase vowels",L1)
print("List of words starting with uppercase vowels".L2)
def main():
counts("A quick black elephant enters Into a jungle")
main()

Question 30.
(a) Write a program to print a string in reverse order using the following functions.

• pushstack(stack, character) Function to push a character into the stack
• popstack(stack) Function pop all the elements from the stack
• isempty() Function to check whether the stack is empty or not.

Or
(b) (i) Define a stack.
(ii) Give a few applications of stack.
(iii) Give any two characteristics of stacks.
Answer:

(a) def pushstack(stack. ch):
stack.append(ch)
top=len(stack)-1
return
def popstack(stack):
if isempty(stack):
return
else:
top=len(stack)-1
for a in range(top, -1, -1):
print(stack[a])
return
def isempty(stack):
if stack==[]:
return True
else:
return False
#--------------main-----------------
stk=[]
top=None
str=input("Enter a string”)
for a in str:
pushstack(stk, a)
print("----------Reverse-------------")
popstack(stk)

Or
(b) (i) A stack is a data structure that allows the addition and removal of elements in a particular order.
Every time an element is added, it goes on the top of the stack and the only element that can be removed is the element that was at the top of the stack.
(ii) Applications of stack

• Expression evaluation
• Backtracking (game playing, finding paths, exhaustive searching).
• Memory management, run-time environment for nested language features.

(iii) Characteristics of Stacks:

• It is a LIFO data structure.
• The insertion and deletion happen at one end. i.e. from the top of the stack.

Question 31.
Consider the following table ORDERS:

(a) Write statements to:
(i) Display the field names, their type, size, and constraints.
(ii) Display details of orders where order price is in the range 500 to 1500
(iii) Write a command to increase the price of all orders by 15%.
Or
(b) (i) Name the constraint that will restrict both NULL and DUPLICATE values in the O_Id Field
(ii) Display details of orders of customer “Hansen”
(iii) Display the customer names in uppercase and month number of order dates.
Answer:

(a) (i) DESCRIBE ORDERS;
(ii) SELECT * FROM ORDERS WHERE OrderPrice BETWEEN 500 AND 1500;
(iii) UPDATE ORDERS SET OrderPrice = OrderPrice + OrderPrice*0.15;
Or
(b) (i) Primary key
(ii) Select * FROM ORDERS WHERE Customer="Hansen";
(iii) Select Ucase(Customer), month(OrderDate) from Orders;

Section D
(4 × 4 = 16)

Question 32.
(A) (i) Write names of some common Exceptions.
(ii) What output will the following code produce?

try:
d={"A":[10,20],"B":[30,40],"C":[50,60]}
print(d[“E”])
except KeyError:
print(“Key does not exist”)
else:
print(Got the value")
finally:
print(“Accessing dictionary values”)

Or
(B) (i) When is the IndexError exception raised?
(ii) What output will the following code produce:

try:
L=[20,23,12,45,89]
print(L[15])
except IndexError:
print('Index out of range')
finally:
print('Code ends')

Answer:
(A) (i) IOError, KeyError, NameError
(ii) Output
The key does not exist
Accessing dictionary values
Or
(B) (i) If a sequence is tried to be accessed outside its existing indices, a KeyError occurs.
(ii) Output
Index out of range
code ends

Question 33.
A CSV file “Bikes.csv” stores details of bikes with their bike names, brand names, and costs.
Record structure of “Bikes.csv”
BID Bname Brand Cost
Write a program using two functions to operate the file data.
PutBike() To accept data of more bikes and store them in the file “Bikes.csv”.
SearchBike(bikeid) To open the file “Bikes.csv” and display details of the bike whose id is supplied as the parameter to the function.
Answer:

import pickle
def PutBike():
f=open("Bikes.csv","ab")
ans='y'
bid= " "
bname= " "
brand= " "
cost=0.0
while ans=='y':
bid=input("Enter bike id:")
bname=input("Enter bike name:")
brand=input("Enter brand: ")
cost=float(input("Enter cost"))
blst=[bid, bname, brand.cost]
pickle.dump(blst.f)
ans=input("Continue(y/n)")
f.close()
def SearchBike(bikeid):
f=open("Bikes.csv"."rb")
while True:
try:
blst=pickle.load(f)
if blst[0]=bikeid:
print(blst)
break
except EOFError:
print(“No such bike!!!”)
f.close()

Question 34.
Consider the following tables PRODUCT and CLIENT.and answer the following questions:

Write SQL queries for statements.
(i) To display the details of those Clients, whose City is Delhi.
(ii) To display the details of products, whose Price is in the range of 50 to 100 (both values included).
(iii) To display the product name and the manufacturer whose Price is more than 100.
(iv) (A) Display the client names and the corresponding product names.
Or
(B) Write a query to display the client name, city, and corresponding product name and price for prices > 80.
Answer:

(i) SELECT * FROM CLIENT WHERE City ‘Delhi’;
(ii) SELECT * FROM PRODUCT WHERE Price BETWEEN 50 AND 100;
(iii) SELECT ProductName, Manufacturer FROM PRODUCT WHERE Price > 100;
(iv) (A) Select clientname, productname from client, product where clinet.P_ID= product.P_ID;
Or
(B) Select clientname, city, productname, price from client, product where clinet.P_ID= product.P_ID and price>80;

Question 35.
(i) What is Python – MySQL connectivity?
(ii) Consider the structure of the table Doctor given below.
Doctor
Doctor_id(p)
Doctor_Name
Hospital_id(F)
Joining_Date
Specialty
Salary
Experience.
Write Python code to create the above table.
Use the following for connectivity:
host=localhost
Userid=HosAdmin
Password=HosAdmin@123
Database=XYZHospital
Answer:
(i) The process of connecting a Python application to a MySql database to exchange information is called Python – MySQL connectivity.

(ii) import MySQLdb
db = MySQLdb.connect(host='localhost', user='HosAdmin', passwd='HosAdmin@123', db='XYZHospital')
cursor = db.cursor()
cursor.execute("DROP TABLE IF EXISTS DOCTORS")
sql = " " "
CREATE TABLE Doctors (
Doctor_Id INT NOT NULL PRIMARY KEY,
Doctor_Name CHAR(50) NOT NULL,
Hospital_Id INT NOT NULL,
Jointng_Date DATE NOT NULL,
Speciality CHAR(50),
Salary FLOAT,
Experience FLOAT
)
" " "
cursor.execute(sql)
cursor.close()
db.close()

Section E
(2 × 5 = 10)

Question 36.
(a) What does tell() method do?
(b) A Binary file “Registration.dat” exists storing details of students who have been registered for CBSE board exams. The file stores the following data of students:
RegnNo StudName class No of subjects
Write a program using two functions to operate the file data.
AddRegistration() To accept more student registration data and store them in the binary file keeping existing registration data.
CountRegistrations() Display the count of registrations using the functions.
Answer:
(a) tell() method tells you the current position of the cursor within the file.

Syntax file_object.tell()
(b) import pickle
def AddRegistration():
f=open("Registration.dat","ab")
ans='y'
rno=" "
sname=" "
class=" "
Nos=0
while ans=='y':
rno=input("Enter registration no..")
sname=input("Enter student name ")
class=input("Enter class")
Nos=int(input(“Enter number of subjects :”))
reglst=[rno,sname,class,Nos]
pickle.dump(reglst.f)
ans=input("Continue(y/n)")
f.close()
def CountRegistrations():
f=open("Registration.dat"."rb")
count=0
try:
while True:
phonelst=pickle.load(f)
count+=1
print(“Number of registrations:”, count)
except EOFError:
break
f.close()
AddRegistration()
CountRegistrations()

Question 37.
Expertia Professional Global (EPG) is an online corporate training provider company for IT-related courses. The company is setting up its new campus in Mumbai. You as a network expert have to study the physical locations of various buildings and the number of computers to be installed. In the planning phase, provide the best possible answers for the queries (a) to (e) raised by them.

(a) Suggest the most appropriate building, where EPG should plan to install the server.
(b) Suggest the most appropriate building-to-building cable layout to connect all three buildings for efficient communication.
(c) Which type of network out of the following is formed by connecting the computers of these three buildings?
(i) LAN
(ii) MAN
(iii) WAN
(d) Write the difference between LAN and MAN.
(e) Expand the following
(i) WAN
(ii) MAN
Or
Expand the following.
(i) FTP
(ii) XML
Answer:
(a) EPG should install the server in the Faculty Studio Building as it has the maximum number of computers.
(b)

(c) (i) LAN (Local Area Network).
(d) A LAN is a local area network of computers connected within a small area, such as a room, a building, or a campus.
A MAN is a metropolitan area network spread across a city within a range of approximately 60 km.
(e) (i) WAN: Wide Area Network
(ii) MAN: Metropolitan Area Network
Or
(i) FTP: File Transfer Protocol
(ii) XML: Extensible Markup Language.