Q1. What is a set in Python?
A set is an unordered, mutable collection of unique, hashable elements. Created with curly braces or set(). Example:
s = {1,2,3,3}Q2. How do you add and remove elements from a set?
Add with add(element). Remove with remove(element) (raises error if not present) or discard(element) (no error). Pop removes an arbitrary element. Clear empties the set. Example:
s.add(5)
s.discard(10)
item = s.pop()Q3. What are the common set operations?
Union (| or union()), intersection (& or intersection()), difference (- or difference()), symmetric difference (^ or symmetric_difference()). They return new sets or modify in-place. Example:
a = {1,2,3}
b = {3,4,5}
print(a | b) # {1,2,3,4,5}
print(a & b) # {3}Q4. What is the difference between set and frozenset?
set is mutable; frozenset is immutable. frozenset can be used as dictionary keys and as elements of another set. They support the same methods except those that modify the set.
Q5. Can a set contain lists? Why or why not?
No, sets require hashable elements. Lists are mutable and unhashable, so they cannot be stored in a set. You can use tuples (immutable) instead.