Python Basics— Concepts, Formulas & Shortcuts
- Immutable types: int, float, str, tuple, frozenset. Mutable: list, dict, set.
- Variables are names bound to objects, not boxes holding values — assignment rebinds the name.
- Lists are mutable and use []; tuples are immutable and use (); tuples can be dictionary keys, lists cannot.
- "is" compares identity (same object); "==" compares value.
- Default mutable arguments are created ONCE at function definition — the classic def f(x, lst=[]) bug.
- Indentation is syntax in Python, not style — inconsistent indentation is a runtime error, not a warning.
Python Basics Practice Questions with Answers
Attempt each question first, then open the explanation. All 8 questions below are free to read and require no signup.
Q1.Which of these Python types is immutable?
Easy- Alist
- Bdict
- Ctuple
- Dset
Python Basics question 1 of 8+Show Answer & Explanation
Answer: C. tuple
Explanation: Tuples cannot be modified after creation. Lists, dicts and sets are all mutable.
Q2.What is the output of: print(type([]))
Easy- A<class 'list'>
- B<class 'tuple'>
- C<class 'array'>
- DError
Python Basics question 2 of 8+Show Answer & Explanation
Answer: A. <class 'list'>
Explanation: [] creates an empty list, so type() reports <class 'list'>.
Q3.What does the expression 7 // 2 evaluate to in Python 3?
Easy- A3.5
- B3
- C4
- D3.0
Python Basics question 3 of 8+Show Answer & Explanation
Answer: B. 3
Explanation: // is floor division on integers, giving the integer 3. Use / for true division, which returns 3.5.
Q4.What is the output of: print("Python"[-2:])
Moderate- Aon
- Bho
- CPy
- Dthon
Python Basics question 4 of 8+Show Answer & Explanation
Answer: A. on
Explanation: Negative indexing starts from the end, so [-2:] returns the last two characters, "on".
Q5.What does "is" compare in Python?
Moderate- AValues
- BObject identity (memory address)
- CTypes only
- DString content
Python Basics question 5 of 8+Show Answer & Explanation
Answer: B. Object identity (memory address)
Explanation: "is" checks whether both names refer to the same object; "==" checks value equality.
Q6.What is the result of: len({1, 2, 2, 3, 3, 3})
Easy- A3
- B4
- C6
- DError
Python Basics question 6 of 8+Show Answer & Explanation
Answer: A. 3
Explanation: A set stores only distinct elements, so duplicates collapse and the length is 3.
Q7.What is the output of: def f(x, lst=[]): lst.append(x); return lst — calling f(1) then f(2)?
Difficult- A[1] then [2]
- B[1] then [1, 2]
- C[1, 2] then [1, 2]
- DError
Python Basics question 7 of 8+Show Answer & Explanation
Answer: B. [1] then [1, 2]
Explanation: The default list is created once at function definition and is shared across calls, so the second call returns [1, 2]. Use lst=None as the fix.
Q8.Which keyword is used to define an anonymous function in Python?
Easy- Adef
- Blambda
- Cfunc
- Danon
Python Basics question 8 of 8+Show Answer & Explanation
Answer: B. lambda
Explanation: lambda creates a small anonymous function, e.g. square = lambda x: x * x.
Python Basics — Frequently Asked Questions
What is the difference between a list and a tuple?+
A list is mutable, slightly larger in memory and cannot be used as a dictionary key. A tuple is immutable, marginally faster to iterate and hashable, so it can be a dict key or set element.
What does "is" do differently from "=="?+
"is" checks whether two names refer to the same object in memory; "==" checks whether the values are equal. Two separate lists with identical contents are == but not is.
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