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Quiz: Functions with Parameters and Scope

Test your understanding of default parameters, keyword arguments, scope, and pure functions with these questions. Click "Show Answer" to reveal the correct answer and explanation.

1. What is a default parameter value in a Python function?

  1. The value a parameter holds when the function returns None
  2. A value the function uses automatically when the caller does not provide an argument for that parameter
  3. The first argument passed to a function when it is called
  4. A parameter that is required and must always be provided by the caller
Show Answer

The correct answer is B. A default parameter value is defined in the def line using parameter=default. When someone calls the function without providing that argument, Python automatically uses the default. When they do provide a value, that value overrides the default. This makes functions flexible — they work with or without certain arguments.

Concept Tested: Default Parameter Values

2. Which function call uses a keyword argument?

  1. draw_polygon(6, 80, "red")
  2. draw_polygon(sides=6, color="red")
  3. draw_polygon("red", 6, 80)
  4. draw_polygon(6)
Show Answer

The correct answer is B. A keyword argument uses the parameter's name followed by = and a value in the function call: sides=6 and color="red". Keyword arguments can be supplied in any order because Python matches them by name, not by position. Option A uses positional arguments, which must be in the correct order.

Concept Tested: Keyword Arguments

3. What is the scope of a variable?

  1. How many characters long the variable's name is
  2. How large the value stored in the variable is
  3. Which parts of the program can see and use the variable
  4. How many times the variable is used in the program
Show Answer

The correct answer is C. Scope describes where in your program a variable is visible and accessible. A variable created inside a function has local scope — it only exists while that function runs. A variable created outside all functions has global scope — it is visible throughout the entire program.

Concept Tested: Local Scope and Global Scope

4. What happens when you try to use a local variable outside the function that created it?

  1. The variable keeps its last value and can be used anywhere
  2. Python prints the value automatically without needing print()
  3. Python raises a NameError because the variable does not exist outside the function
  4. The variable becomes a global variable after the function runs
Show Answer

The correct answer is C. A local variable only exists while its function is running. When the function finishes, the local variable disappears. Trying to use it afterward causes a NameError: name 'variable' is not defined. This is by design — local variables prevent naming conflicts between functions.

Concept Tested: Local Scope and Global Scope

5. What does the global keyword inside a function tell Python?

  1. Create a brand-new local variable with that name inside this function
  2. Delete the global variable when the function finishes
  3. Use the variable that exists in the global (outer) scope, not create a new local one
  4. Print the variable's value to the output when the function is called
Show Answer

The correct answer is C. Without global, if you assign to a variable inside a function, Python creates a new local variable that shadows the global one. Writing global score inside a function tells Python "I mean the score that lives outside, not a new local one" — so assignments to score inside that function actually change the global variable.

Concept Tested: global Keyword

6. What output does this program produce?

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speed = 10

def reset():
    speed = 0
    print("Inside:", speed)

reset()
print("Outside:", speed)
  1. Inside: 0 then Outside: 0
  2. Inside: 10 then Outside: 10
  3. Inside: 0 then Outside: 10
  4. An error because speed is defined twice
Show Answer

The correct answer is C. Inside reset(), speed = 0 creates a new local variable named speed — it does NOT change the global speed. So inside the function, speed is 0. But outside, the global speed is still 10. This is a common naming conflict that causes confusing bugs; using global speed inside the function would fix it if you actually wanted to change the global.

Concept Tested: Local Scope and Global Scope

7. By convention, how do Python programmers write the name of a constant?

  1. Starting with a lowercase letter, like maxSpeed
  2. Surrounded by double underscores, like __max_speed__
  3. In ALL_CAPS with underscores, like MAX_SPEED
  4. Starting with an uppercase letter, like MaxSpeed
Show Answer

The correct answer is C. Python programmers use ALL_CAPS with underscores to signal that a variable is a constant — a value that should never be changed after it is set. Examples: MAX_SPEED = 10, CANVAS_WIDTH = 400. Python does not enforce this; it is a naming convention that tells other programmers "treat this as a fixed rule."

Concept Tested: Constants by Convention

8. Which rule applies when defining a function that has both required parameters and default parameters?

  1. Default parameters must come before required parameters
  2. Required parameters must come before default parameters
  3. You cannot mix required and default parameters in the same function
  4. Default parameters must all have the same default value
Show Answer

The correct answer is B. Required parameters (those without defaults) must come first in the function definition, followed by parameters with default values. For example: def greet(name, greeting="Hello"): is valid. Writing def greet(greeting="Hello", name): would cause a SyntaxError because the required parameter name comes after the default parameter.

Concept Tested: Default Parameter Values

9. What is a pure function?

  1. A function that only uses numbers, never strings
  2. A function defined with def pure: instead of def
  3. A function that always produces the same output for the same inputs and does not change anything outside itself
  4. A function that only calls other functions and never uses print()
Show Answer

The correct answer is C. A pure function always returns the same result given the same arguments, and it does not change any variables outside its own scope (no side effects). Pure functions are easier to test and debug. In contrast, a function that modifies a global variable, prints to the screen, or draws on a canvas has side effects.

Concept Tested: Pure Functions vs Side Effects

10. What is the fastest way to swap the values of variables a and b in Python?

  1. a = b then b = a
  2. temp = a, then a = b, then b = temp
  3. a, b = b, a
  4. swap(a, b)
Show Answer

The correct answer is C. Python supports multiple assignment that evaluates the right side completely before assigning, making a, b = b, a a safe one-line swap. Option A loses the original value of a. Option B (the temporary variable approach) is correct but takes three lines. Option D is not a built-in Python function.

Concept Tested: Swapping Variables