Python Coding Practice - 3 (31 - 45 Questions)

Q31. Which statement is true about tuples?

Think about whether you can change elements after creation.

Answer: Tuples are immutable
Explanation: Once created, tuple elements cannot be changed; lists are mutable.

Q32. Which tuple method returns the index of a value?

Method name suggests position.

Answer: index()
Explanation: tuple.index(value) returns the first index of value; count() returns occurrences.

Q33. Unpack values a,b from tuple t = (1,2).

t = (1, 2)
= t

Use comma-separated variable names on the left.

Answer: a, b
Explanation: a, b = t assigns 1 to a and 2 to b via tuple unpacking.

Q34. Create a set from list lst = [1,2,2,3] to remove duplicates.

lst = [1,2,2,3]
s = (lst)

Use the constructor that creates unique-element collection.

Answer: set
Explanation: set(lst) converts the list to a set, removing duplicate values.

Q35. Which method adds a single element to a set?

One element vs iterable of elements.

Answer: add()
Explanation: set.add(x) inserts a single element; update() accepts an iterable to add multiple elements.

Q36. Which operation gives elements common to both sets A and B?

Think of overlap between sets.

Answer: intersection
Explanation: A & B or A.intersection(B) returns elements present in both sets.

Q37. Create a dictionary with key "name" and value "Alice".

d = {: "Alice"}

Keys are strings and must be quoted.

Answer: "name"
Explanation: Dictionary keys that are strings must be quoted: {"name": "Alice"}.

Q38. Safely get value for key 'age' with default 0.

d = {"name":"A"}
age = d.( 'age', 0 )

Method returns default if key missing.

Answer: get
Explanation: d.get('age', 0) returns 0 if 'age' is not present, avoiding KeyError.

Q39. Update dictionary d with key 'age' = 25 using a method.

d = {"name":"A"}
d.({"age":25})

Method merges another dict into this one.

Answer: update
Explanation: d.update({"age":25}) adds or updates key-value pairs in the dictionary.

Q40. Remove key 'name' and return its value.

d = {"name":"A", "age":20}
val = d.( "name" )

Method removes key and returns its value.

Answer: pop
Explanation: d.pop('name') removes the key and returns its associated value.

Q41. Remove duplicates from list while preserving order.

lst = [1,2,2,3,1]
seen = set()
res = [x for x in lst if (x not in seen and (seen.add(x) or True))]
# The expression uses seen.add(x) to track seen items

Use a set to track seen items inside a comprehension.

Answer: Use comprehension with seen.add(x) trick
Explanation: The comprehension keeps first occurrences and preserves order by checking membership in a set and adding when first seen.

Q42. Which list method removes an element by value?

One removes by value, another by index.

Answer: remove()
Explanation: list.remove(value) deletes the first matching value; pop() removes by index and returns it.

Q43. Which method splits a string into words?

Method returns a list of substrings.

Answer: split()
Explanation: s.split() splits on whitespace by default and returns a list of words.

Q44. Fill in to count character frequencies using dict.get.

s = "aba"
freq = {}
for ch in s:
  freq[ch] = freq.(ch, 0) + 1

Use a safe dictionary access method with default value.

Answer: get
Explanation: freq.get(ch, 0) returns current count or 0 if missing, then adds 1.

Q45. Access the city of user 'u1' from nested dict users = {'u1':{'name':'A','city':'X'}}

users = {'u1':{'name':'A','city':'X'}}
city = users[]['city']

Use the outer key as a string inside brackets.

Answer: "u1"
Explanation: users["u1"] returns the inner dict; ['city'] accesses the city value.