Practice Paper

5.0

Reason — The given code calculates the square root of 25 using the math.sqrt() function from the math module, resulting in 5.0 since sqrt() returns a floating-point number. Applying abs() to a positive number like 5.0 doesn't alter the value, thus the final output remains 5.0.

A writerow function allows us to write a single record into each row of a CSV file.

A primary key in a table does not accept null or duplicate values. A primary key is a set of one or more attributes/fields that uniquely identifies a tuple/row in a table. It must contain unique values, i.e., non-redundant, and cannot be re-declared or left null.

The domain name is www.income.in indicating the network domain hosting the website, while the URL is http://www.income.in/home.aboutus.html, specifying the specific page or resource within that domain.

Telnet protocol is used to create a connection with a remote machine.

2.3

Reason — The random.randrange(4) function returns a randomly selected integer from the range [0, 1, 2, 3], which includes integers only. It cannot return a floating-point number like 2.3.

x = int("Enter value of x:") #Error 1
for in range[0, 10]: #Error 2
    if x = y #Error 3
        print("They are equal") 
    else:
        Print("They are unequal") #Error 4

Error 1 — The input() function is missing from the code to prompt the user for input.

Error 2 — The syntax of the range() function uses parentheses () rather than square brackets [] and the variable y is missing in the for loop declaration (for y in range(0, 10):).

Error 3 — The comparison operator in the if statement has = (assignment) instead of == (equality comparison) and colon (:) is missing at the end.

Error 4 — The print function should be written with a lowercase 'p' for proper syntax.

The corrected code is:

x = int(input("Enter value of x:"))
for y in range(0, 10):
    if x == y:
        print("They are equal") 
    else:
        print("They are unequal")

DELETE FROM INVENTORY;

This statement will delete all rows from the INVENTORY table, freeing up storage space, but it will not remove the structure or schema of the table.

A computer or device that requests resources or data from a server is called client.

The readlines() method returns a list of lines from a file.

The two advantages of using an Optical Fibre cable over an Ethernet cable are as follows:

1. Optical Fibre cables provide higher bandwidth compared to Ethernet cables.
2. Optical Fibre cables can transmit data over longer distances without experiencing signal degradation or loss compared to Ethernet cables.

In file handling, the "w" mode is used to open a file for writing. If the file exists, it will be overwritten. If the file does not exist, a new file will be created with the specified name.

INSERT IN STUDENT (RNO, MARKS) -- Error 1  
VALUE (5, 78.5); -- Error 2

Error 1 — The correct syntax in SQL for inserting data into a table is "INSERT INTO", not "INSERT IN".

Error 2 — The correct keyword used in SQL to specify the values being inserted into the table is "VALUES", not "VALUE".

The corrected code is:

INSERT INTO STUDENT(RNO, MARKS) 
VALUES (5, 78.5);

0
1
2
3
4

(a) LIFO — Last-In First-Out

(b) FIFO — First-In First-Out

Both A and R are true and R is the correct explanation of A.

Explanation
It is essential to check for overflow conditions before executing a Push operation on a stack to ensure that the stack has enough space to accommodate the new element. Similarly, checking for underflow conditions before executing a Pop operation is necessary to prevent deleting elements from an empty stack. An underflow condition indicates an empty stack, while an overflow condition indicates a stack that has reached its maximum capacity and cannot accept more elements.

Both A and R are true and R is the correct explanation of A.

Explanation
In the expression ('x' and 'y' or not 7), both 'x' and 'y' are non-empty string literals, hence they are evaluated as True, and 7 is a non-zero number, also evaluated as True. Therefore, this expression results in 'y'. In Python, when evaluating expressions in a Boolean context, such as conditions in if statements, non-empty strings, non-zero numbers, and non-None values are considered True, while empty strings, numeric zero (0), and None are considered False.

A primary key is a set of one or more attributes or fields that uniquely identify a tuple or row in a table.

A foreign key is a non-key attribute whose value is derived from the primary key of another table in a database.

A candidate key that is not the primary key is called an alternate key.

All attribute combinations inside a relation that can serve as primary key are candidate keys as they are candidates for the primary key position.

The given code opens a file named "VIVO.txt" in read mode and reads its entire content into a variable F1. It then calculates the length of this content using len() and prints the result, which is 30 characters long. However, when it tries to read the next 5 characters from the file using F1.read(5), no characters are left to read since the file pointer is at the end the file. As a result, data remains an empty string.

30

n = int(input(Enter an integer:)) # Error 1
for i in range(1, 11): 
m = n * j # Error 2
print(m; End = '') # Error 3

Error 1 — The quotes around the input message are missing.

Error 2 — The for loop body lacks proper indentation, and the loop variable should be 'i' instead of 'j'.

Error 3 — In Python, a comma (,) is used to separate arguments not semicolon (;), and the first letter of end in the print() function should be lowercase.

The corrected code is :

n = int(input("Enter an integer:")) 
for i in range(1, 11):
    m = n * i
    print(m, end = ' ')

ere l o otP

voice[20 : : -2]: Starting from index 20, the expression goes till the end of the string in reverse order with a step size of -2.

3

The code initialize two dictionaries, d1 and d2, with key-value pairs. Then, it updates d2 with the key-value pairs from d1, overwriting the value of key 'B' in d2 with 'Banana' from d1 and adding the new key-value pair 'A' mapped to 'Avocado'. Finally, it prints the length of d2, which is 3 since d2 now has three key-value pairs after the update operation.

1 : 1800
sum is 16800
2 : 18400
sum is 33400
3 : 34600
sum is 49600

The given code initializes a list L5 with five elements. It then sets begin to 1 and sum to 0. The loop iterates for values 1, 2, and 3. In each iteration, the code adds the element at index c of L5 to sum, prints the c and updated sum, and then adds ten times the first element of L5 to sum and prints the value of sum.

1. The two SQL commands will produce the same result when there are no duplicate values in the Director column of the MOVIES table. If every Director value in the table is unique, both commands will return the same set of distinct Director values.

2. The two SQL commands will produce different results when there are duplicate values in the Director column of the MOVIES table. The first command with DISTINCT will only return unique Director values, omitting duplicates, whereas the second command without DISTINCT will return all Director values, including duplicates.

(a)

SELECT E.ENO, E.ENAME, E.SALARY, D.DNAME
FROM EMPLOYEE E, DEPARTMENT D
WHERE E.DEPT = D.DEPT AND (E.AGE BETWEEN 25 AND 35);

+-----+--------+--------+-----------+
| ENO | ENAME  | SALARY | DNAME     |
+-----+--------+--------+-----------+
|   3 | NALINI |  60000 | COMPUTERS |
|   5 | SURYA  |  58000 | ENGLISH   |
+-----+--------+--------+-----------+

(b)

SELECT D.DNAME, E.ENAME
FROM EMPLOYEE E, DEPARTMENT D
WHERE E.ENO = D.HOD;

+-----------+---------+
| DNAME     | ENAME   |
+-----------+---------+
| COMPUTERS | MONA    |
| ECONOMICS | MUKHTAR |
| ENGLISH   | SURYA   |
+-----------+---------+

(c)

SELECT ENAME, SALARY, ZONE, (SALARY * 30/100) AS INCOME_TAX
FROM EMPLOYEE;

+---------+--------+-------+------------+
| ENAME   | SALARY | ZONE  | INCOME_TAX |
+---------+--------+-------+------------+
| MONA    |  70000 | EAST  | 21000.0000 |
| MUKHTAR |  71000 | WEST  | 21300.0000 |
| NALINI  |  60000 | EAST  | 18000.0000 |
| SANAJ   |  65000 | SOUTH | 19500.0000 |
| SURYA   |  58000 | NORTH | 17400.0000 |
+---------+--------+-------+------------+

Let the "salary.dat" file contain following sample data:

[[101, 'Aditi', 25000], [102, 'Jatin', 19000], [103, 'Minaz', 28000]]

import pickle
def countrec(file_name):    
    f1 = open(file_name, 'rb')
    while True:
        try:
            employees = pickle.load(f1)
            for employee in employees:
                if (employee[2] > 20000):
                    print("Employee ID:", employee[0], "Name:", employee[1], "Salary:", employee[2])
        except EOFError:
                    break
    f1.close()
countrec("salary.dat")

Employee ID: 101 Name: Aditi Salary: 25000
Employee ID: 103 Name: Minaz Salary: 28000

(i) The attribute best suited to be declared as a Primary Key in the CUSTOMER table is CNo (Customer Number). It uniquely identifies each customer in the table.

(ii)

SELECT * FROM TRANSACTION
WHERE TYPE = "Credit";

+------+-----+--------+--------+------------+
| DEPT | CNO | AMOUNT | TYPE   | DOT        |
+------+-----+--------+--------+------------+
| T001 | 101 |   1500 | Credit | 2017-11-23 |
| T003 | 102 |   3000 | Credit | 2017-06-10 |
| T004 | 103 |  12000 | Credit | 2017-09-12 |
+------+-----+--------+--------+------------+

(iii)

SELECT C.CNO, C.CNAME, T.DOT
FROM CUSTOMER C, TRANSACTION T
WHERE C.CNO = T.CNO AND T.AMOUNT >= 2000; 

+-----+--------------+------------+
| CNO | CNAME        | DOT        |
+-----+--------------+------------+
| 103 | LISA THOMAS  | 2017-05-12 |
| 102 | SURBHI SINHA | 2017-06-10 |
| 103 | LISA THOMAS  | 2017-09-12 |
+-----+--------------+------------+

(iv) Mehak will use "MAX()" function to display the last date of transaction (DOT) from the table TRANSACTION for the customer having CNO as 103.

SELECT MAX(DOT) AS Last_Transaction_Date
FROM TRANSACTION
WHERE CNO = 103;

+-----------------------+
| Last_Transaction_Date |
+-----------------------+
| 2017-09-12            |
+-----------------------+

(i) Sonia should use the "open" method to connect to the "cust.csv" file in append mode.

(ii) Sonia should use the file object "f" to connect to the file.

(iii) Line 3 starts a while loop using while True:. This creates an infinite loop that allows Sonia to repeatedly input customer data and add records to the CSV file until she chooses to stop.

(iv) Sonia should use the "writerow" method to write a single row (list of values) to the CSV file.

(v) Line 5 reads the Sonia's input for whether she want to add more records to the CSV file.

(i) Microwave links would be the most suitable choice for setting up the network because of their resilience to hilly terrain, high reliability, and cost-effective deployment compared to wired and radio links.

(ii) Video conference would be the best communication method for doctors at the village hospital to consult senior doctors at the base hospital. Video conferences allow for real-time interaction, visual assessment of patients, and the sharing of medical data, making them more effective for remote consultations compared to email, SMS, or telephone calls.

(iii) POP3 (Post Office Protocol version 3) is used to receive emails. POP3 allows users to download emails from a server to their local device and manage them offline.

(iv)

(a) VoIP — Voice over Internet Protocol

(b) HTTPS — Hypertext Transfer Protocol Secure

(v) The advantages of star topology are as follows:

1. It is easy to detect faults in this network as all computers are dependent on the central hub.
2. The rate of data transfer is fast as all the data packets or messages are transferred through central hub.

196#25#

In the given code, the variable p is initially set to 8, and a function sum is defined with two parameters q and r, each having default values. When the function sum(p) is called, it overrides the default value of q with the value of p, resulting in q becoming 8. Inside the function, p is calculated as the square of the sum of q and r, which evaluates to 196. The function then prints 196# due to the end='#' parameter in the print statement. Subsequently, the function sum(r=3, q=2) is called with specific values for q and r, which are 2 and 3 respectively. Inside this call, p is calculated as 25 and printed as 25#. Therefore, the output of the code is 196#25#.

#Statement 1 — cursor = conn.cursor()
#Statement 2 — cursor.execute(qry)
#Statement 3 — conn.commit()

The completed code is as follows:

import mysql.connector as mysql
def sql_data(): 
    conn = mysql.connect(host = "localhost",
                        user = "root", 
                        password = "A5_b23",
                        database = "school")
    cursor = conn.cursor()  # Statement 1 - to create the cursor object
    rno = int(input("Enter Roll Number: "))
    qry = "DELETE FROM student WHERE RollNo={}".format(rno)
    cursor.execute(qry)  # Statement 2 - to execute the query
    conn.commit()  # Statement 3 - to make the deletion in the database permanent
    print("Record deleted")

Serialization is the process of transforming data or an object in memory (RAM) into a stream of bytes called byte streams. These byte streams, in a binary file, can then be stored on a disk, in a database, or sent through a network. The serialization process is also called pickling.

Deserialization or unpickling is the inverse of the pickling process, where a byte stream is converted back into a Python object.

(i) Shreya should import the "pickle" module in Line 1 to work with binary file.

(ii) Shreya should open the file in write-binary mode ("wb") in Line 2 to add data to the file.

(iii) Shreya should fill in Line 3 with "rb" to read data from a binary file.

(iv) Shreya should use close() in Line 4 to close the file after reading the data.