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Quiz: More Booleans and Conditionals

Test your understanding of truthiness, short-circuit evaluation, ternary expressions, and compound conditions with these questions. Click "Show Answer" to reveal the correct answer and explanation.

1. Which of the following values is considered "falsy" in Python?

  1. "False" (the string with text)
  2. [0] (a list containing zero)
  3. 1 (the integer one)
  4. [] (an empty list)
Show Answer

The correct answer is D. In Python, an empty list [] is falsy — it is treated as False in a boolean context. "False" (a non-empty string) is truthy, [0] (a list with one item) is truthy, and 1 is truthy. The complete list of falsy values includes: False, 0, 0.0, "", [], {}, and None.

Concept Tested: Truthiness and Falsiness

2. How can you use truthiness to check if a string name is not empty?

  1. if name == True:
  2. if name != "":
  3. if name:
  4. if len(name) != 0:
Show Answer

The correct answer is C. Because empty strings are falsy and non-empty strings are truthy, if name: is True when name contains text and False when it is empty. This is more Pythonic (idiomatic Python style) than explicitly comparing with != "" or checking len(name) != 0. All three options B, C, and D produce the same result, but C is the preferred style.

Concept Tested: Truthiness and Falsiness

3. What is short-circuit evaluation with and?

  1. Python evaluates the right side first to save time
  2. Python stops evaluating an and expression as soon as the left side is falsy, without checking the right side
  3. Python runs both sides of and at the same time in parallel
  4. Python caches the result so it never runs the same expression twice
Show Answer

The correct answer is B. With and, if the left operand is falsy, the overall expression can never be True, so Python returns the left value immediately without evaluating the right side. This prevents potential errors — for example, data and data.upper() won't crash if data is None, because the short-circuit stops before calling .upper().

Concept Tested: Short-Circuit Evaluation

4. What does the expression name or "stranger" return when name = ""?

  1. True
  2. "" (the empty string)
  3. "stranger"
  4. An error, because you cannot use or with strings
Show Answer

The correct answer is C. or short-circuits on a truthy left side, but "" is falsy, so Python continues to the right side and returns "stranger". This is a useful default-value pattern: value or default returns value if it is truthy, otherwise returns default. When name = "Monty", the expression returns "Monty" because it is truthy.

Concept Tested: Short-Circuit Evaluation

5. What is the correct way to check if result is None?

  1. if result == None:
  2. if result = None:
  3. if result is None:
  4. if result.isNone():
Show Answer

The correct answer is C. For None, True, and False, Python style recommends using is instead of ==. is checks identity (whether two names refer to the exact same object in memory), while == checks equality in value. Since None is a singleton in Python (there is only one None object), is None is the correct and Pythonic way to check for it.

Concept Tested: Checking for None with is

6. What does this ternary expression evaluate to when score = 85?

1
grade = "pass" if score >= 70 else "fail"
  1. "fail"
  2. None
  3. True
  4. "pass"
Show Answer

The correct answer is D. A ternary expression has the form value_if_true if condition else value_if_false. When score = 85, the condition score >= 70 is True (85 is at least 70), so the expression evaluates to "pass". If score were 65, the condition would be False and the result would be "fail".

Concept Tested: Ternary Expression

7. What is the difference between implicit and explicit type conversion?

  1. Implicit conversion is slower; explicit conversion is faster
  2. Implicit conversion happens automatically (e.g., int + float → float); explicit conversion uses functions like int() or str()
  3. Implicit conversion requires import; explicit conversion is built in
  4. Implicit conversion only works with numbers; explicit conversion works with any type
Show Answer

The correct answer is B. Implicit conversion (also called coercion) happens automatically when Python decides the conversion is safe — for example, 3 + 2.5 converts 3 to 3.0 automatically, giving 5.5. Explicit conversion is when you deliberately call int(), float(), str(), or bool() to control the conversion yourself.

Concept Tested: Implicit vs Explicit Conversion

8. What does x, y = input("Enter x and y: ").split() do?

  1. Asks the user for two separate inputs with two prompts
  2. Gets one line of input from the user, splits it on spaces, and assigns the two parts to x and y
  3. Creates a list [x, y] from the split input
  4. Raises an error because split() cannot be chained directly with input()
Show Answer

The correct answer is B. input() returns a string of everything the user typed. .split() splits it on whitespace, producing a list. Multiple assignment then unpacks that list into the variables. If the user types 3 7, the result is x = "3" and y = "7" (still strings — you need int() to convert them for math).

Concept Tested: Reading Multiple Inputs

9. Which compound condition checks that age is between 13 and 17 (inclusive)?

  1. if age > 13 or age < 17:
  2. if age == 13 and age == 17:
  3. if 13 <= age <= 17:
  4. if age >= 13 or age <= 17:
Show Answer

The correct answer is C. Python supports chained comparisons that read like math: 13 <= age <= 17 checks that age is at least 13 AND at most 17. This is equivalent to age >= 13 and age <= 17. Options A and D using or would be true for almost any age, and option B (using == and and) is impossible — no value can equal both 13 and 17 simultaneously.

Concept Tested: Compound Conditions

10. Which value is NOT falsy in Python?

  1. None
  2. 0
  3. "0" (the string containing zero)
  4. []
Show Answer

The correct answer is C. "0" is a non-empty string containing one character — the digit zero. Non-empty strings are truthy in Python, regardless of what characters they contain. The number 0 (integer), None, and [] (empty list) are all falsy. This distinction between the number zero and the string "0" is a common source of confusion.

Concept Tested: Truthiness and Falsiness