Computer Science: CUET Mock Test - 4 - CUET MCQ

A Python variable is a reserved memory location to store values. In other words, a variable in a python program gives data to the computer for processing. Variables cannot, however, be named the same as keywords (as in case with "try" which is a python variable). Variables cannot contain any special character except "_". They cannot start with numbers and can only contain alphabets, numbers, and underscore (_)

The correct answer is Select * from Stulibrary order by StulD Asc;

Key PointsAn educational institute in Delhi uses a DBMS to store student details. The database named 'school-record' has two tables:

• Student: Stores general student information
• Stulibrary: Tracks issued books

SELECT * FROM Stulibrary ORDER BY StuID ASC;
Explanation:

• SELECT *: This clause retrieves all columns (*) from the Stulibrary table.
• FROM Stulibrary: This clause specifies the table from which data will be retrieved (Stulibrary).
• ORDER BY StuID: This clause sorts the results based on the StuID column.
• ASC: This keyword specifies ascending order for sorting (StuID values from lowest to highest).

The correct answer is BookID, Issued date

Key PointsIn the context of the Stulibrary table, the choice of primary key would typically depend on how the data is structured and the specific requirements of the application. The primary key is a unique identifier for each record in a database table. From the information given, no explicit mention of the primary key configuration is made, but we can infer the most logical option based on common practices.

• Option 1) BookID: While BookID could uniquely identify each book, it may not uniquely identify each record in the Stulibrary table if the same book can be issued multiple times (which is likely in a library scenario).
• Option 2) BookID, StuID: This combination could be considered if a book could only be issued to a student once at any time. However, the same student could potentially issue the same book multiple times at different periods, making this combination insufficient to uniquely identify each record.
• Option 3) BookID, Issued_date: This combination is more likely to uniquely identify each record in the Stulibrary table because it considers both the BookID and the Issued_date. A book can be issued to any number of students over time, but a specific BookID would not be issued to more than one student on the same date, assuming each record represents a unique issuing event.
• Option 4) Issued_date: Just the Issued_date alone would not be sufficient to uniquely identify each record because multiple books can be issued on the same date.

Given this context, Option 3) BookID, Issued_date is the most plausible choice for the primary key of the Stulibrary table, as it best fulfills the uniqueness requirement across all records, considering that the same book can be issued on different dates to either the same student or different students.

The correct answer is Select BookID from Stulibrary where Return_date is NULL;

Key PointsThis query fetches the BookID of books from the Stulibrary table where the Return_date is NULL, indicating that the books have been issued but have not yet been returned.

• SELECT BookID: This retrieves only the `BookID` column, focusing on book identification.
• FROM Stulibrary: This specifies the `Stulibrary` table as the source of data.
• WHERE Return_date is NULL: This crucial part filters the results. A `NULL` value in the `Return_date` column indicates that the book has not been returned yet.

The correct answer is StuAadhar

Key PointsAn alternate key in database terminology is a candidate key that is not chosen as the primary key but is still unique and can identify each record in a table. For the Student table, the ideal alternate key would be an attribute that uniquely identifies each student, aside from the primary key (which we may assume to be something like StuID if following common conventions).

• StuName is generally not unique because different students can share the same name.
• StuContact could be unique, as typically each student would have a unique contact number. However, this depends on the policy of the organization (e.g., whether parents' contact numbers are used for younger students).
• StuAadhar is a highly likely candidate for uniqueness. The Aadhar number is a unique identifier issued by the UIDAI to residents of India, and it is meant to be a unique identifier for each individual.
• StuClass would not be unique as many students belong to the same class.

Given these options, the most definitive and universally unique across all possible scenarios would be: StuAadhar
This assumes that StuAadhar refers to the Aadhar number, which is unique to every individual in India. As such, it would serve as an excellent alternate key, assuming that uniqueness and the ability to identify each record in the table are the primary criteria.

The correct answer is Select Issued_date from Stulibrary group by Issued date having count(*) > 5;

Key PointsIn SQL, when you want to filter groups of data resulting from a GROUP BY clause, you should use the HAVING clause instead of the WHERE clause. The WHERE clause is used to filter rows before they are grouped, while the HAVING clause filters groups after they have been created by GROUP BY.

Given the description of the queries and the requirement to display dates on which the number of issued books is greater than 5:

• Option 1) is incorrect because it uses where count(*) > 5 after the GROUP BY clause, which is a syntax error. The correct keyword for setting conditions on groups is HAVING.
• Option 2) is incorrect because it groups by Return date instead of Issued_date. We are interested in counts of books issued on particular dates, not their return dates.
• Option 3) is correct. This query correctly uses GROUP BY Issued_date followed by HAVING count(*) > 5. It correctly aggregates the data by the issuance date and then filters to find only those dates where more than 5 books were issued.
• Option 4) has the same issue as Option 1 with an added mistake: it uses where instead of HAVING for filtering aggregated results and incorrectly groups by Return date.

So, the correct option is: Select Issued_date from Stulibrary group by Issued_date having count(*) > 5;
This SQL query groups the records by Issued_date and filters for those dates where the total count of issued books is greater than 5.

​Binary search: ​ Search a sorted array by repeatedly dividing the search interval in half. Begin with an interval covering the whole array. If the value of the search key is less than the item in the middle of the interval, narrow the interval to the lower half. Otherwise, narrow it to the upper half. Repeatedly check until the value is found or the interval is empty.

Binary search is a fast search algorithm with run-time complexity of Ο(log n). This search algorithm works on the principle of divide and conquer. A binary search looks for a particular item by comparing the middlemost item of the collection. If a match occurs, then the index of the item is returned.

Algorithm;
int binarySearch(int arr[ ], int l, int r, int x)
{ if (r >= l) {

if (arr[mid] == x)
return mid;

if (arr[mid] > x)
return binarySearch(arr, l, mid - 1, x);

return binarySearch(arr, mid + 1, r, x);
}
return -1;
}

So as per the question, She X is found in the first iteration of the binary search.

Here l=4, r=0

mid= (4 + 0) / 2

mid= 4/2

mid= 2

By default, the array index starts from 0. So the 1st element of an array is at 0th index.

In the first iteration, it found means, so the element is found at index 3.

a[2]=40

Hence the correct answer is 40.

The correct answer is Modulation, Demodulation

Key Points

• MODEM:
  • It stands for Modulation, Demodulation
  • The modem is an electronic device that is used by a computer for sending and receiving information over telephone lines.
    • Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of Analog waves.
    • A modem converts Analog to Digital and vice versa.
    • It allows a computer, router, or switch to connect to access, connect internet.
    • It takes the Analog signal from a telephone line are cable wire and converts it in the form of the digital form (0s and 1s) and vice-versa.
    • A modulator is a circuit that combines two different signals in such a way.
    • A demodulator is an electronic circuit that is used to recover the information content from the modulated carrier wave.
    • In electronics, the multiplexer selects one of several Analog or Digital input signals and further devices the line of the selected input.

The correct option is 1

Concept:-

An IPv6 address is 128 bits long and is divided into eight 16-bit fields, each separated by a colon. In contrast to IPv6 addresses, which use dotted-decimal notation, each field must include a hexadecimal number.Key Points

• The basic IPv6 header and the IPv6 extension headers are two types of headers defined by the IPv6 protocol.
• Separate extension headers are added between the IPv6 header and the transport-layer header in a packet to store IPv6 options.
• Until a packet reaches its final destination, most IPv6 extension headers are not reviewed or processed by any router along its delivery path.
• IPv6 extension headers, unlike IPv4 options, can be any length. Furthermore, a packet carrier's options are not restricted to 40 bytes.

The figure, IPv6 Basic Header Format:-

The correct answer is Statement I is false but Statement II is true

Key PointsStatement I:

• This statement attempts to articulate the so-called "empirical rule" or "rule of thumb" for understanding the relative positions of mean, median, and mode in a skewed distribution. However, it does so incorrectly.
• The more accurate formulation is that in a skewed distribution, the mean is usually pulled in the direction of the skew, further away from the median than the mode is.
• So, in a positively skewed distribution, the mean is greater than the median, which is greater than the mode (mean > median > mode), and vice versa for a negatively skewed distribution. The statement's assertion that the median is always found between the mean and the mode is therefore not accurate.

Statement II:

• This statement is correct. The range of a dataset is a measure of its dispersion or variability and is indeed calculated as the difference between its maximum and minimum values. This gives a rough idea of the spread of the dataset but does not account for how data is distributed between these two extremes.

The correct answer is All of the above

Key Points

• Create a file: In terms of a database this typically refers to creating a table or a database itself. The process of creating a table involves defining its name, fields (columns), and the type of data that each field will contain. This is done using SQL statements such as CREATE DATABASE or CREATE TABLE depending on the operation you want to perform.
• Delete a file: In a DBMS, to 'delete a file' usually means to delete a table or a database. This is performed using SQL statements like DROP TABLE or DROP DATABASE. Doing so will remove those entities from the DBMS, along with all of the data they contain.
• Retrieve a file: In database terminology, 'retrieving a file' is typically synonymous with querying data from a table. SQL contains a number of commands like SELECT that allows users to fetch and display the data from one or multiple tables stored in the DB.

So when comparing to data/file operations in a regular filesystem, the DBMS allows similar functionality but instead of 'files', we have structured 'tables' or 'databases'.

A bus topology is a type of network topology in which all devices are connected to a single cable called a bus, not in ring topology. A star topology is a type of network topology in which all devices are connected to a central hub or switch not in a bus topology. Both are not correct.

Data manipulation languages are divided into two types, procedural programming and declarative programming.

In MAN, different LANs are connected through a local telephone exchange. Some of the widely used protocols for MAN are RS-232, X.25, Frame Relay, Asynchronous Transfer Mode (ATM), ISDN (Integrated Services Digital Network), OC·3 lines (1.55 Mbps), ADSL (Asymmetrical Digital Subscriber Line). These protocols are quite different from those used for LANs.

The rewind() function sets the file position to the beginning of the file for the stream pointed to by stream. It also clears the error and end-of-file indicators for stream.

• Client-server architecture is an architecture in which devices are connected to a central server, which provides services to clients. Clients request services from the server, which then provides a response.
• Peer-to-peer architecture is an architecture in which devices communicate directly with each other without a central server. Each device can act as both a client and a server.
• Service-oriented architecture (SOA) is an architecture in which services are exposed as independent components that can be accessed over a network. Services can be combined to create more complex applications.
• Cloud architecture is an architecture in which resources are provisioned dynamically and accessed over a network. It allows users to access resources such as storage and computing power on-demand.

In this program, getc() function within the while loop will read the characters from TCY.c one by one and display on the screen through the variable Tch.

The tell() method can be used to get the position of File Handle. It returns the current position of the file object. This method takes no parameters and returns an integer value.

The append() method adds an item to the end of the list.

The following program, print((1,2) + (3,4)) gives:
For the given program, we have two tuples, and we are printing the concatenation of these tuples.
i.e print((1, 2) + (3, 4))
A collection of Python objects separated by comma is called a Tuple.
In this, we are using the concatenation operator +, to join the two tuples.
So, (1,2,3,4) is the answer.

Following is the various Applications of Stack in Data Structure:

• Evaluation of Arithmetic Expressions
• Backtracking
• Delimiter Checking
• Reverse a Data
• Processing Function Calls

Non-Procedural DML or High level DML requires a user to specify what data are needed without specifying how to get those data.

Insert is a widely-used command in the Structured Query Language (SQL) data manipulation language (DML) used by SQL Server and Oracle relational databases. The insert command is used for inserting one or more rows into a database table with specified table column values.

White hat hackers are security professionals who follow ethical and legal behavior. Their objective is to help improve security.

Communication bandwidth that has the highest capacity and is used by microwave, cable and fibre optic lines is known as broadband.

The append() method in Python adds a single item to the existing list.

The len function returns the length of the stack, i.e. number of items in stack. The value 0 itself means that the stack is empty.

This will call the function pop() by passing the stack 'Country' as an argument. The function pop is already defined in the given code as: def pop (Country):.

The '2' in the given 'for' statement is the step value which specifies the difference between two consecutive values in the range. Here, the step value is used to refer to the index position of the items in stack. To insert the alternate element, the step value will be taken as 2.

pop() removes the last value from the stack and returns it.