Solved 2025 Sample Question Paper CBSE Class 12 Computer Science (083)

False

Reason — The Python interpreter handles syntax errors during code execution, but it does not handle logical errors. Logical errors, also known as semantic errors, occur when the code is syntactically correct but does not produce the expected output due to incorrect logic or algorithm. These types of errors are caught during the testing and debugging phase, not during code execution by the interpreter.

#THONPROGRAM

Reason — The replace() method in Python searches for a specified substring and replaces it with another. In the given code, the substring 'PY' in the string "PYTHONPROGRAM" is replaced with the character '#'. As a result, the string "PYTHONPROGRAM" becomes "#THONPROGRAM", and that's the output displayed.

not(True) and False

Reason —

1. not(True) and False evaluates to False and False, which is False.
2. True or False evaluates to True.
3. not(False and True) evaluates to not(False), which is True.
4. True and not(False) evaluates to True and True, which is True.

['I', 'ter', 'atio', 'al']

Reason — The code defines a string country = 'International' and uses the split("n") method to split the string at each occurrence of the letter "n". This breaks the string into a list of parts: ['I', 'ter', 'atio', 'al'], with each occurrence of "n" removed and the remaining substrings stored as separate elements in the list. The print() function then outputs this list.

ce lo

1. The code message[-2::-2] starts from the second-last (-2) character of the string "World Peace", which is "c".

2. It moves backwards in steps of 2 to select every second character going towards the start of the string.

3. The traversal goes as follows:

   • Index -2: Character is "c".
   • Index -4: Character is "e".
   • Index -6: Character is a space (" ").
   • Index -8: Character is "l".
   • Index -10: Character is "o".

4. The output is "ce lo".

False

Reason — In the above code, tuple1 is initially assigned the tuple (1, 2, 3), and tuple2 references the same tuple. When the line tuple1 += (4, ) is executed, it modifies tuple1 to (1, 2, 3, 4) because the += operator creates a new tuple rather than modifying the existing one. Thus, tuple1 now contains (1, 2, 3, 4), while tuple2 remains (1, 2, 3). Therefore, the expression tuple1 == tuple2 evaluates to False.

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

Reason — In Python dictionaries, keys must be accessed individually or as a single key. The expression my_dict['apple', 'banana'] attempts to use a tuple as a key (i.e., ('apple', 'banana')), which does not exist in my_dict. As a result, this will raise an Error. The other statements will not raise exceptions; my_dict.get('orange') will return 30, my_dict['apple'] = 20 will update the value for the key 'apple', and print(str(my_dict)) will print the dictionary as a string.

Removes the first occurrence of value x from the list.

Reason — The list.remove(x) method in Python searches for the first occurrence of the value x in the list and removes it. If the specified value is not found, it raises an Error.

3

Reason — In a table, the primary key uniquely identifies each record, and alternate keys also uniquely identify records but are not the primary key. In this case, with one primary key and two alternate keys, the table will have three candidate keys in total: one primary key and two alternate keys. Candidate keys are potential keys that can uniquely identify records in a table.

file.seek(0)

Reason — To move the file pointer to the beginning of the file, we can use the seek() method. When we pass 0 as the offset to this function, it moves the file pointer to the beginning of the file.

So the complete code is:

file = open("example.txt", "r")
data = file.read(100)
file.seek(0)  # Move the file pointer to the beginning of the file
next_data = file.read(50)
file.close()

False

Reason — The finally block in Python is always executed after the try block, regardless of whether an exception occurred or not.

12#15%

Reason —

1. The variable c is initially set to 10.
2. The function add() is defined. Inside this function, the global keyword is used to indicate that the variable c refers to the global variable defined outside the function.
3. Inside add(): When add() is called:
   • The value of c (which is 10) is accessed.
   • It is then incremented by 2, making c equal to 12.
   • The new value of c (12) is printed, followed by a # symbol.
4. After calling the function, the global c is now 12. However, it is then explicitly set to 15.
5. Finally, the new value of c (15) is printed, followed by a % symbol.

The SQL command that can change the degree of an existing relation (table) is ALTER TABLE.

Details of all products whose names start with 'App'

Reason — The SELECT * statement indicates that every column of data should be returned for each matching record. It uses the LIKE operator with the pattern 'App%', where the % wildcard represents any sequence of characters. Therefore, this query will return details of all products from the products table where the product_name starts with 'App', including any characters that may follow.

CHAR

Reason — The CHAR data type in SQL is used to store fixed-length strings. When a value is stored in a CHAR field, it is padded with spaces to fit the specified length.

count()

Reason — The count() aggregate function is used to find the cardinality of a table, which refers to the number of rows in that table.

FTP

Reason — The File Transfer Protocol (FTP) is used for transferring files over the Internet. It allows users to upload, download, and manage files on remote servers.

Gateway

Reason — A gateway is a network device that connects two networks that use different protocols, enabling communication between them.

Packet switching is a method of data transmission where data is broken into smaller packets before being sent over the network. Each packet can take different routes to reach the destination, allowing multiple packets from various sources to share the same network resources simultaneously.

A is true but R is false.

Explanation
Positional arguments must be passed in the order they are defined in the function signature in Python. Python does not automatically assign default values to positional arguments. Default values must be explicitly defined in the function signature, if not provided, the function will raise an error.

A is true but R is false.

Explanation
A SQL SELECT command can have both WHERE and HAVING clauses. The WHERE clause filters records before any grouping occurs, while the HAVING clause filters records after grouping. Therefore, they cannot be used interchangeably as they operate at different stages of query execution.

In Python, a mutable object can be changed after it is created (e.g., lists, dictionaries), while an immutable object cannot be modified after its creation (e.g., tuples, strings).

An example of a mutable object from the given options is [1, 2] (list) and {1:1, 2:2} (dictionary). [Write any one]

An example of an immutable object from the options is '123' (string) and (1, 2) (tuple). [Write any one]

1. Arithmetic Operators — +, -

2. Relational Operators — >, ==

1. (a) L1.count(4)
   OR
   (b) L1.sort()

2. L1.extend(L2)
   OR
   (b) L2.reverse()

W#, W#s#

Minimum and maximum possible values of the variable b is 1, 6.

Reason — The code imports the random module and initializes a string variable a with the value "Wisdom". It then generates a random integer b between 1 and 6, inclusive. A for loop iterates over a range from 0 to b in steps of 2, which means it only considers even indices (0, 2, 4) of the string a. In each iteration, it prints the character at the current index i of the string a, followed by a '#' character, without moving to a new line.

For possible values of b:

For b = 1:

• Range: range(0, 1, 2) → Only includes 0
• Step 1: i = 0 → Prints W#
• Final Output: W#

For b = 2:

• Range: range(0, 2, 2) → Only includes 0
• Step 1: i = 0 → Prints W#
• Final Output: W#

For b = 3:

• Range: range(0, 3, 2) → Includes 0, 2
• Step 1: i = 0 → Prints W#
• Step 2: i = 2 → Prints s#
• Final Output: W#s#

For b = 4:

• Range: range(0, 4, 2) → Includes 0, 2
• Step 1: i = 0 → Prints W#
• Step 2: i = 2 → Prints s#
• Final Output: W#s#

For b = 5:

• Range: range(0, 5, 2) → Includes 0, 2, 4
• Step 1: i = 0 → Prints W#
• Step 2: i = 2 → Prints s#
• Step 3: i = 4 → Prints o#
• Final Output: W#s#o#

For b = 6:

• Range: range(0, 6, 2) → Includes 0, 2, 4
• Step 1: i = 0 → Prints W#
• Step 2: i = 2 → Prints s#
• Step 3: i = 4 → Prints o#
• Final Output: W#s#o#

def swap_first_last(tup) # Error 1
    if len(tup) < 2:
    return tup  # Error 2
    new_tup = (tup[-1],) + tup[1:-1] + (tup[0])  # Error 3
    return new_tup

result = swap_first_last((1, 2, 3, 4))
print("Swapped tuple: " result) # Error 4

Error 1 — The function header is missing a colon (:) at the end, which is required to define a function in Python.

Error 2 — The return statement needs to be indented because it is the part of the if block.

Error 3 — Comma should be added after tup[0] to ensure it is treated as a tuple. Without the comma, (tup[0]) is treated as an integer.

Error 4 — Comma should be added in the print statement to properly separate the string from the variable.

The corrected code is:

def swap_first_last(tup):  
    if len(tup) < 2:        
        return tup 
    new_tup = (tup[-1],) + tup[1:-1] + (tup[0],)
    return new_tup

result = swap_first_last((1, 2, 3, 4))
print("Swapped tuple: ", result) 

To prevent duplicate values in a table column while allowing NULL values, we should use the UNIQUE constraint. The UNIQUE constraint ensures that all values in the specified column are different, but it permits multiple NULLs since NULL is considered distinct from any other value.

To ensure that NULL values are not allowed in a table column while allowing duplicate values, we should use the NOT NULL constraint. The NOT NULL constraint ensures that every entry in the specified column must have a value (i.e., it cannot be NULL), but it allows duplicate values.

Advantage

Ease of service — Network extension is easy.

Disadvantage

Central node dependency — Failure of switch/hub results in failure of the network.

SMTP stands for Simple Mail Transfer Protocol.

It is the standard protocol for sending emails across the Internet.

Suppose the file "Emails.txt" contains the following text:

jagan@cmail.com 
aliya@gmail.com 
ali@cmail.net 
sara@cmail.edu 
mahi@yahoo.com.

def display_words():
    file = open("Emails.txt", 'r')
    content = file.read()
    words = content.split()            
    for word in words:
        if '@cmail' in word:
            print(word, end = ' ')
    file.close()
display_words()

jagan@cmail.com ali@cmail.net sara@cmail.edu

Suppose the file "Words.txt" contains the following text:

The quick brown fox jumps over the lazy dog and runs swiftly through the forest

def display():
    file = open("Words.txt", 'r')
    content = file.read()
    words = content.split()
    for word in words:
        if len(word) > 5:
            print(word, end = ' ')
    file.close()
display()

swiftly through forest 

1.

def push_book(BooksStack, new_book): 
  BooksStack.append(new_book)

2.

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

3.

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

def push_even(N):
    EvenNumbers = []
    for num in N:
        if num % 2 == 0:
            EvenNumbers.append(num)
    return EvenNumbers

VALUES = []

for i in range(5):
    VALUES.append(int(input("Enter an integer: ")))

EvenNumbers = push_even(VALUES)

def pop_even():
    if not EvenNumbers:
        print("Underflow")
    else:
        print(EvenNumbers.pop())
pop_even()

def Disp_even():
    if not EvenNumbers:
        print("None")
    else:
        print(EvenNumbers[-1])
Disp_even()

Enter an integer: 10
Enter an integer: 5
Enter an integer: 8
Enter an integer: 3
Enter an integer: 12
12
8

15@
7@
9@

1. Initialization:

• A dictionary d is created with three key-value pairs.
• An empty string str1 is initialized.

2. Iteration:

   The for loop iterates over each key in the dictionary:

• For "apple": str1 becomes "15@\n" (value 15 followed by "@" and a newline).
• For "banana": str1 becomes "15@\n7@\n" (adding value 7 followed by "@" and a newline).
• For "cherry": str1 becomes "15@\n7@\n9@\n" (adding value 9 followed by "@" and a newline).

3. The line str2 = str1[:-1] removes the last newline character from str1, resulting in str2 being "15@\n7@\n9@".

4. Finally, print(str2) outputs the content of str2.

1 #2 #3 #
1 #2 #3 #
1 #

1. The list line contains the values [4, 9, 12, 6, 20].

2. The outer loop iterates over each element (I) in the line list.

   • First Iteration (I = 4):

     I % 5 = 4 % 5 = 4
     Inner Loop Range: range(1, 4) → This generates the numbers 1, 2, 3.
     Output: 1 #2 #3 #

   • Second Iteration (I = 9):

     I % 5 = 9 % 5 = 4
     Inner Loop Range: range(1, 4) → This generates the numbers 1, 2, 3.
     Output: 1 #2 #3 #

   • Third Iteration (I = 12):

     I % 5 = 12 % 5 = 2
     Inner Loop Range: range(1, 2) → This generates the number 1.
     Output: 1 #

   • Fourth Iteration (I = 6):

     I % 5 = 6 % 5 = 1
     Inner Loop Range: range(1, 1) → This generates no numbers (empty range).
     Print: No output for this iteration (just a new line is printed).

   • Fifth Iteration (I = 20):

     I % 5 = 20 % 5 = 0
     Inner Loop Range: range(1, 0) → This generates no numbers (empty range).
     Print: No output for this iteration (just a new line is printed).

3. The final output of the code will be:

1 #2 #3 #
1 #2 #3 #
1 #

(A)

(I)

SELECT Product, SUM(Quantity)
FROM ORDERS
GROUP BY Product
HAVING SUM(Quantity) >= 5;

(II)

SELECT *
FROM ORDERS
ORDER BY Price DESC;

(III)

SELECT DISTINCT C_Name
FROM ORDERS;

(IV)

SELECT SUM(Price) AS Total_Price
FROM ORDERS
WHERE Quantity IS NULL;

OR

(B)

(I) Select c_name, sum(quantity) as total_quantity from orders group by c_name;

+----------+----------------+
| c_name   | total_quantity |
+----------+----------------+
| Jitendra |              1 |
| Mustafa  |              2 |
| Dhwani   |              1 |
+----------+----------------+

(II) Select * from orders where product like '%phone%';

+------+---------+------------+----------+-------+
| O_Id | C_Name  | Product    | Quantity | Price |
+------+---------+------------+----------+-------+
| 1002 | Mustafa | Smartphone |        2 | 10000 |
| 1003 | Dhwani  | Headphone  |        1 |  1500 |
+------+---------+------------+----------+-------+

(III) Select o_id, c_name, product, quantity, price from orders where price between 1500 and 12000;

+------+----------+------------+----------+-------+
| o_id | c_name   | product    | quantity | price |
+------+----------+------------+----------+-------+
| 1001 | Jitendra | Laptop     |        1 | 12000 |
| 1002 | Mustafa  | Smartphone |        2 | 10000 |
| 1003 | Dhwani   | Headphone  |        1 |  1500 |
+------+----------+------------+----------+-------+

(IV) Select max(price) from orders;

+------------+
| max(price) |
+------------+
|      12000 |
+------------+

Let the "Happiness.csv" file contain the following data:

Signiland, 5673000, 5000, 3426
Happiland, 4500000, 4000, 3200
Joyland, 8000000, 6000, 5000
Cheerland, 3000000, 3500, 2500

(I)

def show(): 
    file = open("Happiness.csv",'r') 
    records=csv.reader(file) 
    for i in records: 
        if int(i[1])>5000000: 
            print(i) 
    file.close() 

['Signiland', '5673000', '5000', '3426']
['Joyland', '8000000', '6000', '5000']

(II)

def Count_records(): 
    f = open("Happiness.csv",'r') 
    records=csv.reader(f) 
    count=0 
    for i in records: 
            count+=1 
    print(count) 
    f.close() 

4

(I)

SELECT * FROM FACULTY, COURSES 
WHERE Salary < 12000 AND FACULTY.F_ID = COURSES.F_ID;

(II)

SELECT * 
FROM COURSES 
WHERE Fees BETWEEN 20000 AND 50000;

(III)

UPDATE COURSES
SET Fees = Fees + 500
WHERE CName LIKE '%Computer%';

(IV)

(A)

SELECT FName, LName 
FROM FACULTY, COURSES 
WHERE CName = 'System Design' AND
FACULTY.F_ID = COURSES.F_ID;

OR

(B)

SELECT * 
FROM FACULTY, COURSES;

(I)

import pickle 
 
def input_candidates(): 
    candidates = [] 
    n = int(input("Enter the number of candidates you want to add: ")) 
    for i in range(n): 
        candidate_id = int(input("Enter Candidate ID: ")) 
        candidate_name = input("Enter Candidate Name: ") 
        designation = input("Enter Designation: ") 
        experience = float(input("Enter Experience (in years): ")) 
        candidates.append([candidate_id, candidate_name, designation, 
experience]) 
    return candidates

candidates_list = input_candidates() 
 
def append_candidate_data(candidates): 
    with open('candidates.bin', 'ab') as file: 
        for candidate in candidates: 
            pickle.dump(candidate, file) 
    print("Candidate data appended successfully.") 
 
append_candidate_data(candidates_list)

(II)

import pickle 
 
def update_senior_manager(): 
    updated_candidates = [] 
    try: 
        with open('candidates.bin', 'rb') as file: 
            while True: 
                try: 
                    candidate = pickle.load(file) 
                    if candidate[3] > 10:  # If experience > 10 years 
                        candidate[2] = 'Senior Manager' 
                    updated_candidates.append(candidate) 
                except EOFError:
                    break  # End of file reached 
    except FileNotFoundError: 
        print("No candidate data found. Please add candidates first.") 
        return 
 
    with open('candidates.bin', 'wb') as file: 
        for candidate in updated_candidates: 
            pickle.dump(candidate, file) 
 
    print("Candidates updated to Senior Manager where applicable.")

update_senior_manager() 

(III)

import pickle 
 
def display_non_senior_managers(): 
    try: 
        with open('candidates.bin', 'rb') as file: 
            while True: 
                try: 
                    candidate = pickle.load(file) 
                    if candidate[2] != 'Senior Manager':  # Check if not Senior Manager 
                        print(f"Candidate ID: {candidate[0]}") 
                        print(f"Candidate Name: {candidate[1]}") 
                        print(f"Designation: {candidate[2]}") 
                        print(f"Experience: {candidate[3]}") 
                        print("--------------------") 
                except EOFError: 
                    break  # End of file reached 
    except FileNotFoundError: 
        print("No candidate data found. Please add candidates first.") 
 
display_non_senior_managers()

(I) The most appropriate location for the server inside the MUMBAI campus is ADMIN block because it has maximum number of computers.

(II) Switch is used to connect all the computers within each building.

(III) Cable layout connecting various buildings within the MUMBAI campus is shown below:

For the most efficient data transfer over the network, optical fiber cables are recommended.

(IV) There is no requirement for a repeater as optical fiber cables can transmit signals over longer distances.

(V)

(A) Video Conferencing

Video conferencing is recommended for live communication between the Mumbai and Delhi offices due to its real-time interaction and flexibility making it ideal for effective discussions across distant locations.

OR

(B) The type of network that will be set up among the computers connected in the MUMBAI campus is LAN (Local Area Network).