Lists And 2D Lists

Question 1

What is a list in Python?

Answer 1

A list is a data structure that can store multiple items in one variable.

Example: my_list = [1, 2, 3].

Question 2

How do you access an item in a list?

Answer 2

Use the index, starting from 0.

Example: my_list[1] returns 2.

Question 3

How do you change an item in a list?

Answer 3

Assign a new value to an index.

Example: my_list[0] = 10 changes the first item to 10.

Question 4

How do you add an item to the end of a list?

Answer 4

Use append().

Example: my_list.append(4) adds 4 to the end.

Question 5

How do you insert an item at a specific position in a list?

Answer 5

Use insert(index, value).

Example: my_list.insert(1, 99) adds 99 at index 1.

Question 6

How do you remove an item from a list by value?

Answer 6

Use remove(value).

Example: my_list.remove(3) removes the first 3.

Question 7

How do you remove an item from a list by index?

Answer 7

Use pop(index) or del my_list[index].

Example: my_list.pop(2) removes the item at index 2.

Question 8

How do you loop through a list in Python?

Answer 8

Use a for loop like for item in my_list: to access each item one at a time.

Question 9

What is a 2D list in Python?

Answer 9

A list of lists.

Example: matrix = [[1, 2], [3, 4], [5, 6]].

Question 10

How do you access an item in a 2D list?

Answer 10

Use two indexes.

Example: matrix[1][0] returns 3.

Question 11

How do you change an item in a 2D list?

Answer 11

Use two indexes to assign a value.

Example: matrix[2][1] = 9.

Question 12

How do you loop through a 2D list in Python?

Answer 12

Use nested loops: for row in matrix: and then for item in row:.

Question 13

What are common uses of 2D lists?

Answer 13

Representing data tables, grids, spreadsheets, or game boards like tic-tac-toe.

Question 14

What is the difference between a list and a 2D list?

Answer 14

A list stores a single sequence of items. A 2D list stores lists within a list, forming rows and columns.