CBSE Class 12 Computer Science Sample Paper 2023 Set A

SECTION A

1. State True or False
“Variable declaration is implicit in Python.”
Answer: TRUE

2. Which of the following is an invalid datatype in Python?
(a) Set
(b) None
(c) Integer
(d) Real
Answer: D

3. Given the following dictionaries
dict_exam={"Exam":"AISSCE", "Year":2023}
dict_result={"Total":500, "Pass_Marks":165}
Which statement will merge the contents of both dictionaries?
(a) dict_exam.update(dict_result)
(b) dict_exam + dict_result
(c) dict_exam.add(dict_result)
(d) dict_exam.merge(dict_result)
Answer: A

4. Consider the given expression:
not True and False or True
Which of the following will be correct output if the given expression is evaluated?
(a) True
(b) False
(c) NONE
(d) NULL
Answer: A

5. Select the correct output of the code:
a = "Year 2022 at All the best"
a = a.split('2')
b = a[0] + ". " + a[1] + ". " + a[3]
print (b)
(a) Year . 0. at All the best
(b) Year 0. at All the best
(c) Year . 022. at All the best
(d) Year . 0. at all the best
Answer: A

6. Which of the following mode in file opening statement results or generates an error if the file does not exist?
(a) a+
(b) r+
(c) w+
(d) None of the above
Answer: B

7. Fill in the blank:
______ command is used to remove primary key from the table in SQL.
(a) update
(b) remove
(c) alter
(d) drop
Answer: C

8. Which of the following commands will delete the table from MYSQL database?
(a) DELETE TABLE
(b) DROP TABLE
(c) REMOVE TABLE
(d) ALTER TABLE
Answer: B

9. Which of the following statement(s) would give an error after executing the following code?
S="Welcome to class XII" # Statement 1
print(S) # Statement 2
S="Thank you" # Statement 3
S[0]= '@' # Statement 4
S=S+"Thank you" # Statement 5
(a) Statement 3
(b) Statement 4
(c) Statement 5
(d) Statement 4 and 5
Answer: B

10. Fill in the blank:
_________ is a non-key attribute, whose values are derived from the primary key of some other table.
(a) Primary Key
(b) Foreign Key
(c) Candidate Key
(d) Alternate Key
Answer: B

11. The correct syntax of seek() is:
(a) file_object.seek(offset [, reference_point])
(b) seek(offset [, reference_point])
(c) seek(offset, file_object)
(d) seek.file_object(offset)
Answer: A

12. Fill in the blank:
The SELECT statement when combined with __________ clause, returns records without repetition.
(a) DESCRIBE
(b) UNIQUE
(c) DISTINCT
(d) NULL
Answer: C

13. Fill in the blank:
______is a communication methodology designed to deliver both voice and multimedia communications over Internet protocol.
(a) VoIP
(b) SMTP
(c) PPP
(d) HTTP
Answer: A

14. What will the following expression be evaluated to in Python?
print(15.0 / 4 + (8 + 3.0))
(a) 14.75
(b) 14.0
(c) 15
(d) 15.5
Answer: A

15. Which function is used to display the total number of records from table in a database?
(a) sum(*)
(b) total(*)
(c) count(*)
(d) return(*)
Answer: C

16. To establish a connection between Python and SQL database, connect() is used. Which of the following arguments may not necessarily be given while calling connect() ?
(a) host
(b) database
(c) user
(d) password
Answer: B

Q17 and 18 are ASSERTION AND REASONING 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):- If the arguments in function call statement match the number and order of arguments as defined in the function definition, such arguments are called positional arguments.
Reasoning (R):- During a function call, the argument list first contains default argument(s) followed by positional argument(s).
Answer: C

18. Assertion (A): CSV (Comma Separated Values) is a file format for data storage which looks like a text file.
Reason (R): The information is organized with one record on each line and each field is separated by comma.
Answer: A

SECTION B

19. Rao has written a code to input a number and check whether it is prime or not. His code is having errors. Rewrite the correct code and underline the corrections made.
def prime():
n=int(input("Enter number to check :: ")
for i in range (2, n//2):
if n%i=0:
print("Number is not prime \n")
break
else:
print("Number is prime \n’)
Answer: def prime():
n=int(input("Enter number to check :: ")) #bracket missing
for i in range (2, n//2):
if n%i==0: # = missing
print("Number is not prime \n")
break #wrong indent
else:
print("Number is prime \n”) # quote mismatch

20. Write two points of difference between Circuit Switching and Packet Switching.
Answer: 

OR

Write two points of difference between XML and HTML.
Answer: XML (Extensible MarkupLangauge)
♦ XML tags are not predefined, they are user defined
♦ XML stores and transfers data.
♦ Dynamic in nature
HTML (Hypertext Markup Langauge)
♦ HTML tags are pre-defined and it is a markup language
♦ HTML is about displaying data.
♦ Static in nature

21. (a) Given is a Python string declaration:
myexam="@@CBSE Examination 2022@@"
Write the output of: print(myexam[::-2])
(b) Write the output of the code given below:
my_dict = {"name": "Aman", "age": 26}
my_dict['age'] = 27
my_dict['address'] = "Delhi"
print(my_dict.items())
Answer: (a) @20 otnmx SC@
(b) dict_items([('name', 'Aman'), ('age', 27), ('address', 'Delhi')])

22. Explain the use of ‘Foreign Key’ in a Relational Database Management System. Give example to support your answer.
Answer: A foreign key is used to set or represent a relationship between two relations (or tables) in a database. Its value is derived from the primary key attribute of another relation.
For example:
In the tables TRAINER and COURSE given below, TID is primary key in TRAINER
table but foreign key in COURSE table. 
TRAINER

23.
(a) Write the full forms of the following:
(i) SMTP (ii) PPP
(b) What is the use of TELNET?
Answer: (a) (i) SMTP: Simple Mail Transfer Protocol
(ii) PPP: Point to Point Protocol
(b) TELNET is used to access a remote computer / network.

24. Predict the output of the Python code given below:
def Diff(N1,N2):
if N1>N2:
return N1-N2
else:
return N2-N1
NUM= [10,23,14,54,32]
for CNT in range (4,0,-1):
A=NUM[CNT]
B=NUM[CNT-1]
print(Diff(A,B),'#', end=' ')
Answer: 22 # 40 # 9 # 13 #

OR

Predict the output of the Python code given below:
tuple1 = (11, 22, 33, 44, 55 ,66)
list1 =list(tuple1)
new_list = []
for i in list1:
if i%2==0:
new_list.append(i)
new_tuple = tuple(new_list)
print(new_tuple)
Answer: (22,44,66)

25. Differentiate between count() and count(*) functions in SQL with appropriate example.
Answer: COUNT(*) returns the count of all rows in the table, whereas COUNT () is used with Column_Name passed as argument and counts the number of non-NULL values in a column that is given as argument. Example: Table : EMPL

OR

Categorize the following commands as DDL or DML:
INSERT, UPDATE, ALTER, DROP
Answer: DDL- ALTER, DROP
DML – INSERT, UPDATE

SECTION C

26. (a) Consider the following tables – Bank_Account and Branch:
Table: Bank_Account  


What will be the output of the following statement?
SELECT * FROM Bank_Account NATURAL JOIN Branch;
(b) Write the output of the queries (i) to (iv) based on the table,
TECH_COURSE given below:

(i) SELECT DISTINCT TID FROM TECH_COURSE;
(ii) SELECT TID, COUNT(*), MIN(FEES) FROM
TECH_COURSE GROUP BY TID HAVING COUNT(TID)>1;
(iii) SELECT CNAME FROM TECH_COURSE WHERE
FEES>15000 ORDER BY CNAME;
(iv) SELECT AVG(FEES) FROM TECH_COURSE WHERE
FEES BETWEEN 15000 AND 17000;
Answer: (a) 

(b) (i) DISTINCT TID
101
NULL
102
104
103
(ii) TID COUNT(*) MIN(FEES)
101 2 12000
(iii) CNAME
Digital marketing
Mobile Application Development
(iv) 15500.00

27. Write a method COUNTLINES() in Python to read lines from text file ‘TESTFILE.TXT’ and display the lines which are not starting with any vowel.
Example:
If the file content is as follows:
An apple a day keeps the doctor away.
We all pray for everyone’s safety.
A marked difference will come in our country.
The COUNTLINES() function should display the output as:
The number of lines not starting with any vowel - 1
Answer: def COUNTLINES() :
file = open ('TESTFILE.TXT', 'r')
lines = file.readlines()
count=0
for w in lines :
if (w[0]).lower() not in 'aeoiu'
count = count + 1
print ("The number of lines not starting with any
vowel: ", count)
file.close()
COUNTLINES()

OR

Write a function ETCount() in Python, which should read each character of a text file “TESTFILE.TXT” and then count and display the count of occurrence of alphabets E and T individually (including small cases e and t too).
Example:
If the file content is as follows:
Today is a pleasant day.
It might rain today.
It is mentioned on weather sites
The ETCount() function should display the output as:
E or e: 6
T or t : 9
Answer: def ETCount() :
file = open ('TESTFILE.TXT', 'r')
lines = file.readlines()
countE=0
countT=0
for w in lines :
for ch in w:
if ch in 'Ee':
countE = countE + 1
if ch in 'Tt':
countT=countT + 1
print ("The number of E or e : ", countE)
print ("The number of T or t : ", countT)
file.close()

28. (a) Write the outputs of the SQL queries (i) to (iv) based on the relations Teacher and Placement given below:
Table : Teacher 

(i) SELECT Department, avg(salary) FROM Teacher
GROUP BY Department;
(ii) SELECT MAX(Date_of_Join),MIN(Date_of_Join) FROM
Teacher;
(iii) SELECT Name, Salary, T.Department, Place FROM
Teacher T, Placement P WHERE T.Department =
P.Department AND Salary>20000;
(iv) SELECT Name, Place FROM Teacher T, Placement P
WHERE Gender =’F’ AND T.Department=P.Department;
(b) Write the command to view all tables in a database.
Answer: (a) 
(i) Department Avg(Salary)
Computer Sc 16500.00
History 30000.00
Mathematics 25000.00
(ii) Max(Date_of_Join) Min(Date_of_Join)
2021-09-05 2017-03-04
(iii) Name Salary Department   Place
Randeep 30000  Mathematics  Jaipur
Samira  40000   History          Ahmedabad
Raman  25000   Mathematics  Jaipur
Shyam  30000  History          Ahmedabad
Shiv    21000   Computer Sc  Nagpur
(iv) Name Place
Samira     Ahmedabad
Suman     Ahmedabad
Shalaka    Jaipur
(b) SHOW TABLES;

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