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Python Interview Questions

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1

What is the difference between a list and a tuple? Normal

List is mutable: you can add, remove, or change elements after creation; syntax [1, 2, 3]. Tuple is immutable: once created, you cannot change it; syntax (1, 2, 3). Tuples are slightly faster and use less memory; use them when the collection should not change (e.g. dictionary keys, return values that represent a fixed record).

2

Write a list comprehension that squares even numbers from 0 to 9. Code

[x**2 for x in range(10) if x % 2 == 0]

Result: [0, 4, 16, 36, 64]. You can also do [x**2 for x in range(0, 10, 2)] to iterate only evens.

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35+ questions across Normal (conceptual), Code (write Python), and Logic (design & problem-solving).

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Basics & data structures
3

*args and **kwargs — what are they and when do you use them? Normal

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4

Write code to merge two dicts (Python 3.9+ and older way). Code

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5

When would you use a set vs a list for membership checks? Logic

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Functions & decorators
6

What is a decorator? Give an example. Normal

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7

Write a simple decorator that prints the time a function takes. Code

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8

Generators vs list comprehensions — when to use each? Logic

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OOP & classes
9

@staticmethod vs @classmethod vs instance method? Normal

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10

Implement a context manager that measures time (with statement). Code

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11

Explain MRO (method resolution order) in multiple inheritance. Logic

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Data handling & pandas
12

What is the difference between merge, join, and concat in pandas? Normal

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13

Write code to drop duplicate rows keeping the first occurrence. Code

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14

How would you optimize a pandas pipeline for a large CSV? Logic

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Concurrency & patterns
15

What is the GIL? How does it affect threading vs multiprocessing? Normal

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16

deepcopy vs shallow copy — when does it matter? Normal

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17

Exception handling best practices (broad vs narrow, re-raise). Logic

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