Computer Science: CUET Mock Test - 9 - CUET MCQ

Parentheses, Exponential, Multiplication, Division, Addition, Subtraction
Just remember: PEMDAS, that is, Parenthesis, Exponentiation, Multiplication, Division, Addition, Subtraction. Note that the precedence order of Division and Multiplication is the same.

Types of SQL Commands:

• DDL (Data Definition Language)
• DML (Data Manipulation Language)
• DQL (Data Query Language)
• DCL (Data Control Language)
• Data administration commands
• Transaction control commands

The loop does not terminate as new elements are being added to the list in each iteration.

A queue is a data structure that follows the First-In-First-Out (FIFO) principle. It means the first item added to the queue is the first item to be removed from the queue.

To access only a particular part of a file, functions such as fseek(), rewind(), and ftell() can be used.

The append mode defines the way in which new data is added to the already existing data. The property can be used with both, import and export operations. During import, new table is created in the target database.

The World Wide Web—commonly referred to as www, W3, or the web—is an interconnected system of public web pages accessible through the internet.

Cryptography is the study and practice of techniques for secure communication in the presence of third parties called adversaries. It deals with developing and analyzing protocols which prevents malicious third parties from retrieving information being shared between two entities thereby following the various aspects of information security.

The reverse() method reverses the order of the elements in an array. The reverse() method overwrites the original array.

A right parenthesis makes pop operation to delete the elements in stack till we get left parenthesis as top most element. 3 elements are there in stack before right parentheses comes. Therefore, maximum number of elements in stack at run time is 3.

lengths = list(map(lambda s: len(s), strings))
The above line will count the number of characters in each string and store the result in list lengths. So, in first statement result will be [5,6,6,4] and the result of second statement will be [6,4,5,6].

• Keywords : They have a special meaning in SQL. They are understood as instructions.
• Commands : They are instructions given by the user to the database also known as statements.
• Clauses : They begin with a keyword and consist of keyword and argument.

DDL commands provide definitions for creating table structure, deleting relations and modifying relation schemas.

Some of the most common threats include:

• Malware
• Viruses
• Spyware
• Adware
• Trojan horses
• Worms
• Phishing
• Spear phishing

• There are some codes to handle a file in a programming language:
• myfile=open('student. txt', 'w') is the mode that allows opening a file in write mode.
• myfile=open('student.txt', 'r') is the mode that opens a file in only read mode.
• myfile= open ('student.txt') also allows opening a file in reading mode.

Function Name and Parameter List are parts of a function header in Python.

Full-duplex mode is used when communication in both direction is required all the time. The capacity of the channel, however must be divided between the two directions.
Example: Telephone Network in which there is communication between two persons by a telephone line, through which both can talk and listen at the same time.

The hue parameter in the seaborn library is used to specify the variable to use for color encoding. It allows users to create plots with multiple colors based on a categorical variable. For example, if you have a dataset with different species of flowers and you want to create a scatter plot with different colors for each species, you can use the hue parameter to specify the species variable.

• Bar charts are useful for comparing data across categories or groups.
• Line charts are useful for displaying trends over time or continuous data.
• Scatter plots are useful for showing the relationship between two variables.
• Pie charts are useful for showing parts of a whole or percentages.

Remote Area Network or RAN was a network method that enabled wireless transfer of data via landline, RS232 serial port, cell phone or satellite connections. The Symax 8030 CRM 560 was a Remote Network Interface Module that used this method of linking IO from field devices to local area and remote area networks. The RAN methodlogy is the basis for transmitting data via radio modems.

Correct option is write a sequence of strings
CONCEPT:
writelines() writes a sequence of strings to the file or a list of strings in an opened file.
Syntax:: 
fileObject.writelines( sequence )

Correct option is Multiple

CONCEPT:
Try and Except statement is used to handle errors within our code in Python.
The try block is used to check some code for errors i.e the code inside the try block will execute when there is no error in the program.
Whereas the code inside the except block will execute whenever the program encounters some error in the try block.
A try statement may have more than one except clause, to specify handlers for different exceptions. At most one handler will be executed.

Example:
try:
    //operation which can raise an exception
except OSError:
    print("OS error)
except ValueError:
    print("Could not convert data to an integer.")
except BaseException:
    print("Unexpected")

CONCEPT:
 Type Error occurs when the data type of objects in an operation is inappropriate.
Example dividing an integer with a string.
In the above question, a for loop is executing through the list which tries to increment the value of each element of the list by 1 and store it in variable x.
" x=int(element + 1) " but will result in type error when it tries to increment the element 'a' at index 0 of the list by 1.
This is because 'a' is of type string and we cannot add an integer to a string. 

The correct answer is option 2.

Concept:
Exception:
An exception is an occurrence that happens during program execution that disturbs the regular flow of the program's instructions. When a Python script finds a condition that it cannot handle, it throws an exception. A Python object that reflects an error is known as an exception.
Option 1:EOFError
False, An EOFError is a Python exception that is thrown when methods like input() and raw input() return end-of-file (EOF) without reading any input. EOFError exception is raised when an interpreter finds the requested module definition.
Option 2:ImportError
True,The ImportError is raised when an import statement has trouble successfully importing the specified module. Typically, such a problem is due to an invalid or incorrect path, which will raise a ModuleNotFoundError in Python 3.6 and newer versions.
Example:
import maths
# Here ImportError exception is raised when an interpreter does not find the requested module definition.
It gives an error like,
Traceback(most recent call last): File "", line 1, in import maths Module, not FoundError: No module named ' maths' 
Option 3: IndexError
False, IndexError is a sort of Python exception produced by the system when the index supplied as subscript does not fall within the range of indices of boundaries of a list. This is a run-time exception that must be handled with a try-catch block.
Option 4:IOError
False, IOError stands for Input/Output Error. It happens when the file, file path, or OS activity we're looking for doesn't exist. For example, if you are performing a runtime action on an existent file and the file disappears from the location, Python will raise an IOError.

Hence the correct answer is ImportError.

Concept:
Exception:

• An exception is an occurrence that happens during program execution that disturbs the regular flow of the program's instructions. When a Python script finds a condition that it cannot handle, it throws an exception. A Python object that reflects an error is known as an exception.
• Exception Handlers are programs that are designed to run when a specific exception is thrown.
• Raising an exception involves stopping the usual flow of program execution and navigating to the exception handler. 
• Raise and assert statements are used to raise exceptions.
• Raise is often utilized when an erroneous condition has been recognized or when a condition does not fulfilled. Similar to assert, however, the exception is only triggered if a condition is fulfilled.

​Assert:

• The assert statement is generally used at the beginning of the function or after a function call to check for valid input.
• The assert statement accepts an expression as well as an optional message.
• The assert statement is used to validate the types, values of arguments, and function output.
• The assert statement is used as a debugging tool since it stops the application when an error occurs.

Syntax:
assert <condition>
assert <condition>,<error message>

Raise:
While they try and except blocks are for handling exceptions, the raise keyword on the contrary is to raise an exception.

Syntax:
raise  {name_of_ the_ exception_class}

Hence the correct answer is assert.

CONCEPT:

In Python, there are several built-in exceptions that are raised when errors occur.
To view these built-in exceptions local() function is used which returns a dictionary of the current local symbol table.
dir() is a function that returns a list of the attributes and methods of the object passed to it.

>>> print(dir(locals()['__builtins__']))

CONCEPT:
When we try to access an item using a value that is out of the index range of the list and does not exist then “index out of range” error occurs.
For example, we have a list of 5 elements, the index is in the range of 0 to 4.
list = [18, 12, 33, 42, 15]     {0, 1, 2, 3, 4 }  // are the respective index of the list 
If we try to access index 5 of the list it will result in an IndexError: list index out of range 
as we are trying to access an item using a value that is out of the index range of the list.
In the above question:
Option 1 EOFError // When we ask the user for input using one function input() or raw_input(), but then have not provided any input in the input box results in EOFError.
Option 2 NameError // This error is raised when the identifier is accessed before being defined in the local or global scope.
Option 3 OverFlowError // This error occurs when an arithmetic operation exceeds the limits of the variable type.

Option 4 IndexError // This is the correct option as explained above.

CONCEPT:
In python to read or write a file, we need first to open it and python provides a function open(), which returns a file object.
Using this file object, we can read and write in the file. But in the end, we need to close the file using this same.
If we don’t call the close() function, the file will remain open, and its object will be consuming the memory of our process.
Therefore it is a standard practice to close an open file as a closed file reduces the risk of being unwarrantedly modified or read.
“with statement” creates an execution block and the object created in the with statement will be destroyed or gracefully closed when this execution block ends.

Benefits of calling open() using “with statement”:

• Fewer chances of bugs due to coding error
• Open multiple files in a single “with statement”

The correct option is Syntax Error

CONCEPT:

Syntax errors occur when the programmer does not follow or makes mistake in the syntax of a particular programming language

Common syntax errors in python:

• leaving out a keyword.
• misspelling a keyword.
• leaving out a symbol, such as a comma, brackets, or colon.

Concept:

• We can put an optional else clause along with the try...except clause.
• An except block will be executed only if some exception is raised in the try block.
• But if there is no error then none of the except blocks will be executed. In this case, the statements inside the else clause will be executed.