2.2.1 Branching Statements Extra Practice

What is the purpose of an `if` statement in Python?

• To repeat a block of code

• To check a condition and run code if it's true

• To create variables

• To close a program

Answer explanation

The purpose of an `if` statement in Python is to check a condition and execute a block of code only if that condition is true. This allows for decision-making in the code.

Which keyword begins a basic conditional structure in Python?

• when

• check

• if

• then

Answer explanation

In Python, the keyword 'if' is used to start a basic conditional structure, allowing the execution of code based on whether a condition is true. The other options ('when', 'check', 'then') are not valid keywords for this purpose.

What symbol is required at the end of an `if` line?

• =

• ;

• :

• .

Answer explanation

In Python, an `if` statement must end with a colon (:). This indicates the start of the block of code that will execute if the condition is true. The other options (=, ;, .) are not valid syntax for ending an `if` line.

How does Python structure code blocks under `if`?

• With curly brackets

• With indentation

• With parentheses

• With semicolons

Answer explanation

Python structures code blocks under 'if' using indentation. This means that the code inside the 'if' statement must be indented to indicate that it belongs to that block, unlike other languages that use curly brackets.

When will this code run the print statement? if age >= 18: print("You can vote!")

• When age is 18

• When age is less than 18

• Always

• Never

Answer explanation

The print statement runs when age is 18 or greater. Therefore, it will execute when age is exactly 18, as this meets the condition 'age >= 18'. Thus, the correct answer is 'When age is 18'.

What type of error occurs if the `if` block is not indented?

• NameError

• IndentationError

• TypeError

• LogicError

Answer explanation

An IndentationError occurs in Python when the code is not properly indented. Since the `if` block must be indented to define its scope, failing to do so results in this specific error.

What is the purpose of `elif` in Python?

• To end a conditional

• To run code if `if` is false and another condition is true

• To write a loop

• To test one condition only

Answer explanation

The `elif` statement in Python allows you to check another condition if the preceding `if` condition is false. This enables more complex decision-making by running specific code when additional conditions are met.

Which of the following uses `elif` correctly?

• elif (score >= 90)

• elif score >= 90:

• elif = score > 90:

• else if score > 90:

Answer explanation

The correct usage of `elif` is `elif score >= 90:`. It properly includes a colon at the end and does not use parentheses or an assignment operator. The other options are syntactically incorrect.

What happens if both `if` and `elif` are false?

• The code block under `if` runs

• The code block under `elif` runs

• The code block under `else` runs, if present

• The program crashes

Answer explanation

If both `if` and `elif` conditions are false, the code block under `else` runs, if it is present. This allows for a default action when none of the specified conditions are met.

What happens if none of the conditions in an `if-elif-else` structure are met?

• The program crashes

• The `else` block runs

• Nothing happens

• `elif` becomes `if`

Answer explanation

In an `if-elif-else` structure, if none of the conditions are met, the `else` block runs. This block serves as a default action when all previous conditions fail, ensuring the program continues to execute without crashing.