Python - Introduction

Question 1

What is a variable in Python?

Answer 1

A named reference to a value stored in memory.

Variables store data such as numbers, strings, or lists.

Question 2

How do you assign the value 10 to a variable named x?

Answer 2

x = 10

The = operator assigns values to variables.

Question 3

True or False:

Variable names in Python can start with a number

Answer 3

False.

Variable names must start with a letter or an underscore (_).

Question 4

Which of the following is a valid variable name? 2var, my_var, my-var

Answer 4

my_var

Python variable names cannot start with a number or contain hyphens.

Question 5

Fill in the blank:

To check a variable’s type, use the ____ function

Answer 5

type()

Example: type(10) → <class ‘int’>.

Question 6

What is a string in Python?

Answer 6

A sequence of characters enclosed in quotes.

Strings can use single (‘text’) or double (‘“text”’) quotes.

Question 7

How do you create a multiline string?

Answer 7

Using triple quotes (“"”text””” or ‘'’text’’’).

Example: “"”Hello\nWorld”””.

Question 8

What does len(“Python”) return?

Answer 8

6

The len() function returns the number of characters in a string.

Question 9

True or False:

Strings in Python are immutable

Answer 9

True.

You cannot change characters in an existing string.

Question 10

How do you concatenate two strings a and b?

Answer 10

a + b

Example: “Hello” + “ World” → “Hello World”.

Question 11

List three numeric types in Python.

Answer 11

• int
• float
• complex

Integers are whole numbers, floats have decimals, and complex numbers have real & imaginary parts.

Question 12

What is the output of 5 // 2?

Answer 12

2

// performs floor division, discarding the decimal part.

Question 13

What is the Boolean value of bool(0)?

Answer 13

FALSE

In Python, 0, None, and empty collections evaluate to False.

Question 14

Which function converts a string “10” into an integer?

Answer 14

int(“10”)

Type conversion functions include int(), float(), and str().

Question 15

True or False:

3.0 is an integer in python

Answer 15

False.

It is a float (type(3.0) → <class ‘float’>).

Question 16

What keyword starts an if statement in Python?

Answer 16

if

Example: if x > 0: print(“Positive”).

Question 17

How do you check if x is equal to 10?

Answer 17

if x == 10:

The == operator checks equality.

Question 18

True or False:

elif is **optional **in an if-elif-else statement

Answer 18

True.

elif allows multiple conditions but is not required.

Question 19

Which operator checks if a is not equal to b?

Answer 19

!=

Example: if a != b: print(“Not equal”).

Question 20

Fill in the blank:

if statements use ____ indentation in Python

Answer 20

Whitespace (4 spaces or a tab)

Python uses indentation instead of {}.

Question 21

How do you define an empty list?

Answer 21

[] or list()

Lists store multiple elements in an ordered sequence.

Question 22

What does my_list.append(5) do?

Answer 22

Adds 5 to the end of my_list.

append() modifies the list in place.

Question 23

True or False:

Lists in Python are mutable

Answer 23

True.

You can change, add, or remove elements.

Question 24

What does mylist[1:3] return?

Answer 24

A slice of the list from index 1 to 2.

The end index is exclusive.

Question 25

How do you reverse a list in Python?

Answer 25

**my_list.reverse()** or **my_list[::-1]** ## Footnote .reverse() modifies the list, [::-1] returns a new reversed list.

Question 26

What loop type runs a block of code **multiple times**?

Answer 26

for or while loop ## Footnote Loops iterate over a sequence of items.

Question 27

How do you define a function in Python?

Answer 27

Using **def** ## Footnote Example: def my_function(): pass.

Question 28

# True or False: Functions must always return a value

Answer 28

**False.** ## Footnote Functions without return return None.

Question 29

How do you exit a loop prematurely?

Answer 29

**break** ## Footnote Stops loop execution immediately.

Question 30

What does **continue**do inside a loop?

Answer 30

Skips the current iteration and moves to the next. ## Footnote Useful for filtering elements in loops.

Question 31

What is the **mean** of [2, 4, 6]?

Answer 31

**4** ## Footnote Mean = Sum / Count.

Question 32

# True or False: The median is the middle value of a dataset

Answer 32

**True.** ## Footnote If the dataset size is even, the median is the average of the two middle values.

Question 33

What measure indicates data **spread**?

Answer 33

Standard deviation. ## Footnote Higher standard deviation means more variability.

Question 34

Which function calculates **correlation** in pandas?

Answer 34

**df.corr()** ## Footnote Measures the relationship between variables.

Question 35

What is the **mode**?

Answer 35

The most occurring value. ## Footnote A dataset can have multiple modes.

Question 36

Which chart type is best for showing **trends** over time?

Answer 36

Line chart. ## Footnote Used for continuous data.

Question 37

What is a common mistake when using a **pie chart**?

Answer 37

Using too many slices. ## Footnote Makes it difficult to compare proportions.

Question 38

# True or False: **Bar charts** can represent categorical data

Answer 38

**True.** ## Footnote They compare different categories.

Question 39

How do you label a matplotlib plot?

Answer 39

**plt.xlabel()** and **plt.ylabel()** ## Footnote Ensures clarity in visualizations.

Question 40

What is the primary purpose of a **histogram**?

Answer 40

To show the **distribution** of **numerical data**. ## Footnote Useful for identifying skewness and outliers.