Computer Science: CUET Mock Test - 2 - CUET MCQ

A primary key is a field or set of fields in a table that uniquely identifies each record in the table and cannot be Null. It is used to enforce data integrity and to ensure that there are no duplicate records in the table. A foreign key is a field in one table that refers to the primary key in another table. It is used to establish a relationship between two tables, and it ensures that data in one table is linked to data in another table.

The correct answer is AB*CD/+

Key PointsThe postfix (also known as Reverse Polish Notation - RPN) is a way of writing expressions without the need for parenthesis. It places operators after their operands. To convert the infix expression (A*B + C/D) to postfix, we follow the operands and operators in their order of operation, considering the precedence of operators.

Given infix expression: (A*B + C/D)

• Multiply A and B ((A*B))
• Divide C by D ((C/D))
• Add the results of steps 1 and 2

Following these steps in postfix notation:

• Multiplication of A and B is represented as (AB*)
• Division of C by D is represented as (CD/)
• Addition of the results of the above operations is represented by appending a plus (+) symbol after them.

Therefore, putting it all together, the postfix expression becomes: (AB*CD/+)

So, the correct option is: AB*CD/+

The correct answer is Begining of the file

• File offset position: It's the point within a file where the next read or write operation will occur.
• < r > mode: This mode is designed specifically for reading from a file.

When you open a file in < r > mode, the file offset position is automatically set to the beginning of the file. This means that any subsequent read operations will start from the first byte of the file.

Key Points

• The file offset position can be changed using functions like fseek (in C) or seek (in Python), but it's initially at the beginning in < r > mode.
• Other file opening modes have different default offset positions:
  • < w > mode (write): Sets the offset to the beginning, overwriting existing content.
  • < a > mode (append): Sets the offset to the end, appending new content.
  • < r+ > mode (read and write): Sets the offset to the beginning, but allows both reading and writing.

The correct answer is ZeroDivisionError

1. Function Definition:

• The code defines a function named myDiv(x, y) that attempts to divide x by y.
• It checks for a potential division by zero:
  • If y is equal to 0, it raises a ZeroDivisionError to prevent an invalid operation.
  • If y is not 0, it proceeds with the division and returns the result (x/y).

2. Function Call:

• The code calls the myDiv function with arguments 4 and 0: n = myDiv(4, 0).
• Within the function:
  • The check y == 0 evaluates to True, because y is indeed 0.
  • This triggers the raise ZeroDivisionError statement.
  • The function execution stops immediately, and the ZeroDivisionError is raised.

3. Error Handling:

• The code doesn't have any explicit error handling mechanisms like try-except blocks.
• Therefore, the raised ZeroDivisionError propagates up and terminates the program.
• The print statement print(n) never gets executed.

Output:

• The output you'll see is the error message:
• ZeroDivisionError

Key Points

• Python, like most programming languages, doesn't allow division by zero.
• It raises a ZeroDivisionError to prevent mathematical errors and potential program crashes.
• It's essential to handle potential errors gracefully with exception handling blocks to ensure program robustness.

The correct answer is Full duplex

Key PointsThe Transmission mode is divided into three categories:

• Simplex mode
  • In Simplex mode, the communication is unidirectional, i.e., the data flow in one direction. The radio station is an example of simplex channel
• Half-duplex mode
  • In a Half-duplex channel, direction can be reversed, i.e., the station can transmit and receive the data as well but only one direction at a time. A Walkie-talkie is an example of the Half-duplex mode.
• Full-duplex mode
  • In Full duplex mode, the communication is bi-directional, i.e., the data flow in both the directions. Example of the full-duplex mode is a telephone network.

The correct answer is A, B and D only

Key Points

• A. Reduces data redundancy and saves storage:
  • This is an advantage of databases. By storing data in a centralized location and enforcing data integrity, databases eliminate the need for duplicate copies of data across different files.
• B. Sharing of data is possible:
  • Databases are designed for multi-user access. They provide mechanisms for controlled sharing of data among authorized users.
• C. Difficult to access the data in formatted way:
  • This is not necessarily true. Databases offer structured query languages (SQL) for easy and efficient access to data in a formatted way.
• D. Data inconsistency is reduced to a larger extent:
  • Databases enforce data integrity through constraints and data types, minimizing inconsistencies that can arise with file systems.
• E. Databases are not portable:
  • Modern databases offer portability features, allowing them to be transferred across different platforms with minimal configuration changes.

Therefore, options A, B, and D represent the key advantages of databases over file systems.

Concept

The stability of a sorting algorithm is concerned with how the algorithm treats equal (or repeated) elements.

A sorting algorithm is said to be stable if two objects with equal keys appear in the same order in sorted output as they appear in the input array to be sorted.

Some sorting algorithms are stable by nature like Insertion sort, Merge Sort, Bubble Sort, etc. And some sorting algorithms are not, like Heap Sort, Quick Sort, etc.

The correct option is String.

CONCEPT:

In Python we use readline() and readlines() method to read the content of a file.

readline() method reads a line from the file and return it in the form of the string. It can take a parameter that specifies the maximum number of bytes that can be read from the file. But it cannot read more than one line from the file.

Syntax: file.readline()

Return Value: Returns the next line of the file including the newline character.

readlines() method will append all the lines of a file in the format of a list where each element of the list is a line of the file.

Syntax: file.readlines()

Return Value: A list containing the lines.

To check the type of a return value we can use type() function in python.

Example: Let us open a file named "data.txt" using open function as follows

file = open("data.txt", "r")

lines = file.readlines()

// using readlines() method to read lines of the data.txt file and store it in lines

print(type(lines))

// this will print the type of data stored in lines

The correct answer is option 3.

Concept:

Python is a programming language that is commonly used to create websites and applications, automate operations, and do data analysis. Python is a general-purpose programming language, which means it can be used to develop a wide range of applications and isn't tailored to any particular issue.

• The interpreter parses our Python code before converting it to Python byte code, which it then executes.
• During this initial step of program execution, also known as parsing, the interpreter will look for any incorrect syntax in Python.
• If the interpreter fails to parse our Python code, we have used improper syntax somewhere. The interpreter will try to show us where we made the mistake.
• In Python code, on encountering a syntax error, the Interpreter does not execute the program.

Hence the correct answer is Interpreter.

The correct option is Both w+ and a+

CONCEPT:

To read or write a file, we first need to open it using the open() function, which returns a file object.

Syntax:

open(file, mode)

The "mode" attribute is passed to specify the mode in which we require the file to be opened.

There are several access modes available for the open() function:

w+ Opens the file in writing and reading mode or creates the file if it doesn't exist and opens it in write mode

r+ Opens the file in reading and writing mode but does not create the file if it does not exist.

a+ Opens the file in append and reading mode or creates the file if it doesn't exist and opens it in append mode.

Therefore "Both w+ and a+" mode can be used to write data to a file even if the file does not exist.

The correct answer is (A) is false, (R) is false.

Key Points

• Assertion (A) is INCORRECT. When a file is opened in read mode (< r >), the file offset position is set to the beginning of the file, not the end.
• Reason (R) is INCORRECT. The main purpose of read mode is to access and read existing content from the start of the file, not necessarily to begin reading from the end.

A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume).

(A) MQTT is a lightweight, publish-subscribe protocol that is ideal for low-bandwidth, high-latency networks, making it well-suited for IoT devices that operate in remote areas with limited connectivity.
(B) CoAP is a lightweight protocol designed for constrained devices and low-power networks, making it well-suited for IoT devices that operate on battery power or have limited processing capabilities.
(C) HTTP is a popular protocol used for web-based communication, but it is not as well-suited for IoT devices due to its high overhead and lack of support for low-power networks.
(D) LoRaWAN is a long-range, low-power protocol designed for IoT devices that need to communicate over long distances, making it well-suited for applications like smart agriculture or asset tracking.

Data Definition Language: The SQL DDL provides commands for defining relation schemas, deleting relations, and modifying relation schemas.

In relational model, data is stored in relations (tables) and is represented in form of tuples (rows). RDBMS is used to manage relational database. Relational database is a collection of organized set of tables related to each other, and from which data can be accessed easily.

• In a DBMS, the SQL database language is used to:
• Create the database and table structures
• Perform basic data management chores (add, delete and modify)
• Perform complex queries to transform raw data into useful information

• A subquery is a query that is nested inside another query and is used to retrieve data to be used in the main query.
• A 'Common Table Expression' (CTE) is a named temporary result set that can be used within a query. It is similar to a subquery but is declared separately and can be referenced multiple times within the same query.
• A window function is a function that performs a calculation across a set of rows that are related to the current row. It is used to calculate values such as running totals or moving averages.
• A materialized view is a physical copy of a query result that can be stored and queried later. It is used to improve performance by precomputing expensive queries.

Bubble sort is a simple sorting algorithm that compares adjacent elements and swaps them if they are in the wrong order. It has a worst-case time complexity of O(n²) for both comparisons and swaps, making it inefficient for large collections. Merge sort is a divide-and-conquer sorting algorithm that works by dividing the collection into smaller subcollections, sorting them recursively, and then merging the sorted subcollections to produce the final sorted collection. It has a worst-case time complexity of O(n log n) for both comparisons and swaps, making it efficient for large collections.

while(0) - It is opposite of while(1). It means condition will always be false and ,thus, the code in 'while' will never get executed.

Each character is encoded in the ASCII or Unicode character. So, we can say that Python strings are also called the collection of Unicode characters. In Python, strings can be created by enclosing the character or the sequence of characters in the quotes.

Underflow occurs when the user performs a pop operation on an empty stack.

Instance or extension or database state which is a collection of information stored in a database at a particular moment is called an instance of the database. Thus, it is a dynamic value which keeps on changing.

(A) World Wide Web (WWW) - It is a system of interlinked hypertext documents that are accessed via the Internet. Documents and downloadable media are made available to the network through web servers and can be accessed by programs such as web browsers.
(B) Internet - The Internet, sometimes called simply "the Net," is a worldwide system of computer networks. It is a network of networks in which users at any one computer can, if they have permission, get information from any other computer. Hence, it is a global network of interconnected computers and other devices that use standardized communication protocols.
(C) Cloud Computing - It is a model for delivering on-demand access to shared computing resources over the Internet. It is the delivery of computing services—including servers, storage, databases, networking, software, analytics, and intelligence—over the internet to offer faster innovation and flexible resources.
(D) Machine-to-Machine (M2M) - It is technology that enables direct communication between IoT devices, without the need for human intervention. The main purpose of M2M technology is to tap into sensor data and transmit it to a network.

• Linear Search has a worst-case time complexity of O(n), where n is the size of the input data.
• Binary Search has a worst-case time complexity of O(log n), where n is the size of the input data.
• Interpolation Search has a worst-case time complexity of O(n log n), which is less efficient than O(log n) algorithms like Binary Search.
• The worst-case running time of Depth-First Search (DFS) depends on the graph being traversed. In a graph with n nodes and m edges, the time complexity of DFS is O(n+m), which means that the running time increases linearly with the number of nodes and edges in the graph.

We can use * operator to repeat the tuple values n number of times.
For example:
("abc",)*3 will return ('abc', 'abc', 'abc').

csv is the correct code to fill up the blank in Statement 1, which is to be imported.

writer(fh) should be used in blank space in Statement 3. csv. writer is used to insert data to the CSV file.

writerows() should be used in blank space in Statement 5.
writerows() function writes each sequence in a list as a comma separated line of items in the file.

This code opens a file student.csv in write mode becasue append( ) method is using.
So, correct misssing code is "Student.csv", "w"

Suitable code for blank space in Statement 4 is roll_no, name, class, section.