Computer Science: CUET Mock Test - 5 - CUET MCQ

In Python, we use the hash symbol # to write a single-line comment.

" .py " is the correct extension of the Python file.
.PY file is a program or script written in Python, which is an interpreted object-oriented programming language. It may be written in a text editor and may be edited, but it must be run using a Python interpreter. .PY files are often used to program web servers and other administrative computer systems.

Linear search has a time complexity of O(n), which means that it takes linear time to search an array. This makes it inefficient for large arrays, as the time taken to search the array grows linearly with the size of the array. Therefore, whether linear search is a simple and easy-to-implement algorithm, it is not efficient for large arrays.

SQL stands for Structured Query Language. It lets you access and manipulate databases and became a standard of the American National Standards Institute (ANSI) in 1986, and of the International Organization for Standardization (ISO) in 1987.

Primary key is a key that uniquely identifies each record in a table.
Foreign key is used to establish a relationship between two tables.
Candidate key can be used as a primary key and is unique for each record.
Composite key is composed of two or more columns and is used to uniquely identify each record in a table.

A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Data sent through the internet, such as a web page or email, is in the form of data packets.

The 'readline()' function can be used to read the first line of a text file Myfile. txt. Hence, the correct answer is option 3.

The "a" mode allows you to open a file to append some content to it. If we want to add a new line to it, we can open it using the "a" mode (append) and then, call the write() method, passing the content that we want to append as argument.

ALTER TABLE statement is used to add a new column to an existing table in SQL. INSERT ROW statement is not used to insert the Row to an existing table in SQL. INSERT INTO is used to insert the Row.

No, Python does not support labels and goto. It's a (highly) structured programming language.

Concept of slicing is used in this question. In string slicing, the output is the substring starting from the first given index position i.e. 2 to one less than the second given index position i.e. (8 - 1 = 7) of the given string str1. Hence, the output will be "format".

The process of identifying a slot for the second and further items in the hash table in the event of collision, is called collision resolution.

Yes, All (1), (2) and (3) are the advantages of a database management system.

The binary heap data structure takes O(n) time to build, and the repeated extraction and placement operations take O(log n) time. Hence, the total worst-case time complexity of Heap Sort is O(n log n).

• Selection Sort: O(n²) - This occurs when the array is in reverse sorted order or any other order, as the algorithm has to traverse the entire array to find the minimum element repeatedly.
• Radix Sort: O(nk), where n is the size of the array and k is the number of digits in the largest number.
• Count Sort: O(n+k), where n is the number of elements to be sorted, and k is the range of input values.

In Python, any non-zero value is considered True. So, it will evaluate to true.

r mode is used to open the file.
'NewsLetter.TXT'. It opens a file in reading mode.

line.split( ) method fits the blank in Statement-3 to read data word by word.

file.close( ) is used to close the file. It is important to close the file as soon as you have finished your work with the file.

file.read( ) is fits the blank in Statement-2 as this method returns a string containing all characters in a file.

len(c)<4 is used fits the blank in Statement-4, which displays the word having lesser than 4 characters.

Concept:
The range of frequencies available for data transmission is known as Bandwidth. It is also the amount of data that can be transmitted in a fixed amount of time.

• The bandwidth of digital equipment is commonly measured in bits per second or bytes per second. The bandwidth of analog devices is measured in cycles per second, or HZ.
• Digital bandwidth, or simply bandwidth, is the quantity of data that can be transported from one point to another in a given length of time in computer networks and computer science.
• The range of frequencies filled by a modulated radio-frequency signal is known as bandwidth in electronics, and it is commonly expressed in hertz or as a percentage of the radio frequency.
• The effective bandwidth multiplied by the frequency reuse factor equals the channel bandwidth, where the effective bandwidth is the operating bandwidth correctly scaled by the uplink/downlink ratio.
• The main distinction between the two is that frequency refers to the rate at which a radio signal sends and receives communication signals, whereas bandwidth refers to the difference between the signal's highest and lowest frequencies.

SQL commands are just that: commands. It's used to send and receive data from the database. It can also be used to carry out specific activities, functions, and data queries.

Here are some commands that come under DDL:

• CREATE
• ALTER
• DROP
• TRUNCATE

In the event of a failure, database recovery is the process of restoring the database to a correct (consistent) state.

Three states of database recovery:

• Pre-condition: At any given point in time the database is in a consistent state.
• Condition: Occurs the same kind of system failure.
• Post-condition: Restore the database to the consistent state that existed before the failure.

The correct answer is option 3.

Concept:
print() method:
The print() method outputs the message supplied to the screen or another standard output device. The message can be a string or any other object, which will be transformed into a string before being displayed on the screen.

Syntax:
print(object(s), sep=separator, end=end, file=file, flush=flush)

Explanation:
The given python code is,
print("Hello world"):
The print function prints the data which are there in double-quotes and give the output is Hello world.
print('Hello world'):
The print function prints the data which are there in single quotes and gives the output is Hello world. And python accepts either double quotes or single quotes.
print('\"Hello world'):
The print function prints the data which are there in single quotes and gives the output as "Hello world. \ back ward slash emits after the single or double quotes in the print function.
Hence the correct answer is 
Hello world
Hello world
"Hello world

The correct option is ​Prints the largest odd number in the stack = 9

CONCEPT:
Stack is a data structure that follows last in first out order for insertion and deletion of items.
The insertion and deletion of items take place from one end only using the top pointer.

EXPLANATION:
In the above program, items of the list "a" are pushed into stack "s" if they satisfied the if condition i.e. item%2 !=0. 
Which will push only odd items of the list onto stack "s".
The content in the stack will be as follows:

Stack "s"
Now items of the stack are popped one by one in the while loop (till the stack has some item in it) and compared with the max variable 
#iteration 1 : temp = s.pop() = 1
                     here max < temp, Thus new max = 1.
#iteration 2 : temp = s.pop() = 3
                     here max < temp, Thus new max = 3.
#iteration 3 : temp = s.pop() = 9
                     here max < temp, Thus new max = 9.
#iteration 4 : temp = s.pop() = 5
                     here max > temp, Thus if block does not executes 
Hence max = 9.
The final value of max = 9 will be printed in the end which is the largest odd number in the stack = 9.

The correct answer is option D.

Concept: 
Legend chart element is utilized to identify data series by their color patterns. Legend depicts the colors, patterns, or symbols assigned to the data series. It helps to differentiate the data.
A legend is a portion that describes the graph's components. There is a method in the matplotlib package called legend() that is used to place a legend on the axes. The property Loc in legend() is used to indicate the legend's placement. loc="best" is the default value (upper left).

Syntax:
matplotlib.pyplot.legend([“blue”, “green”], bbox_to_anchor=(0.75, 1.15), ncol=2)
Hence the correct answer is Legend.

• Series() is a function of the Pandas library that can be used for creating a series.
• A function is always used with the dot(.) operator. We cannot use hyphen(-) to use a function of a library.
• Pandas is a library, and not a function by itself. Hence it cannot be followed by a set of round brackets.
• Pandas does not contain any sub-library and the Series() function is directly included in the Pandas library.

The selection sort algorithm sorts an array by repeatedly finding the minimum element from the unsorted part and putting it at the beginning.So, Every pass 1 swap minimum is required.
The selection sort is good for swapping purposes.

According to the question , the array is {7,8,9,6,5}
Applying selection sort :
1st pass - 5 {7,8,9,6} 
2nd pass - 5, 6 {7,8,9} 

3rd pass - 5, 6, 7 {8,9}

4th pass - 5,6,7,8 {9} ( array sorted)
So, we need 4 passes/iterations to sort the array using selection sort.

Bubble sort work by the principle of finding the max element from the array and pushing it to the end.
Applying bubble sort on {7,8,9,6,5}
1st pass- {7,8,6,5} 9 
2nd pass - {7,6,5}  8, 9
3rd pass- {6,5} 7, 8, 9
4th pass - {5} 6, 7, 8, 9 ( array sorted )
So, we need 4 passes to sort the array using bubble sort.
Both selection and bubble sort takes (n-1) passes / iteration to sort the array. 

Bubble Sort is one of the simplest sorting algorithms which works by repeatedly swapping the adjacent elements if they are in the wrong order.
The logic of working- Greatest element of the list will be at the end after the 1st pass.
Compare with the neighbors, if greater then swap it.
Let's take a simple example to understand it better.
Example:
No. of element = 8(70,25,10,75,80,85,90,15)
1st pass - {70,25,10,75,80,85,15} 90 = 7 comparison
2nd pass - {70,25,10,75,80,15} 85,90 = 6 comparison 
3rd pass - {70,25,10,75,15} 80,85,90 = 5 comparison
4th pass- {70,25,10,15}75,80,85,90= 4 comparison
5th pass- {25,10,15}70,75,80,85,90 = 3 comparison
6th pass- {10,15}25,70,75,80,85,90= 2 comparison
7th pass- {10}15,25,70,75,80,85,90 = 1 comparison  (Element list sorted)

So, we need 7 pass to sort 8 element list by bubble sort.(option 4)
FORMULA-  if the number of an element is n, then we need (n-1) passes to sort the element list. 

The correct answer is option C.

Concept:
remove() method:
remove() method in Python can be used to remove files and the os. rmdir() method can be used to delete an empty folder. The shutil.rmtree() method can be used to delete a folder along with all of its files.
This function accepts a single input, which should be a string with the path to the file to be deleted.
If the specified file doesn’t exist a FileNotFoundError error is thrown. If the given path points to a directory, it will throw an IsADirectoryError error.
Example:
Remove the file "testbook.txt":
import os
os.remove("testbook.txt")

Example:
Remove a file from some specific folder is "c:\temp\testboo\python\myfolder":
import os
os.rmdir("c:\temp\testboo\python\myfolder")
Hence the correct answer is remove('file_path').