dictionaries: building, indexing, adding and removing keys

Question 1: What is the correct way to create an empty dictionary in Python?

1. empty_dict = []
2. empty_dict = {}
3. empty_dict = ()
4. empty_dict = set()

Question 2: Which of the following are valid ways to add a key-value pair to an existing dictionary? (Choose all that apply)

1. my_dict['new_key'] = 'new_value'
2. my_dict.add('new_key', 'new_value')
3. my_dict.update({'new_key': 'new_value'})
4. my_dict.insert('new_key', 'new_value')

Question 3: Complete the code to create a dictionary with the following key-value pairs: 'name': 'Alice' and 'age': 30.

person = ______

Question 4: What will be the output of the following code?

my_dict = {'a': 1, 'b': 2}
print(my_dict['b'])

1. 1
2. 2
3. 'b'
4. KeyError

Question 5: Insert the correct code to remove the key 'age' from the dictionary person.

person = {'name': 'Alice', 'age': 30}
______

Question 6: What happens if you try to access a key that doesn't exist in a dictionary using square brackets, like my_dict['nonexistent_key']?

1. The key is added to the dictionary with a value of None.
2. A new key-value pair is added with an empty string as the value.
3. The program raises a KeyError.
4. The program returns None.

Question 7: Which of the following statements about dictionaries are true? (Choose all that apply)

1. Dictionary keys must be unique.
2. Dictionary values must be unique.
3. Dictionary keys can be of any immutable data type.
4. Dictionary values can be of any data type.

Question 8: Arrange the steps to correctly remove a key-value pair from a dictionary and print the updated dictionary.

1. Remove the key 'age'.
2. Print the updated dictionary.
3. Define the dictionary person with keys 'name' and 'age'.

Question 9: Complete the code to retrieve the value associated with the key 'age' from the dictionary person, or return None if the key does not exist.

age = person.______('age')

Question 10: What will be the output of the following code?

my_dict = {'a': 1, 'b': 2, 'c': 3}
my_dict.update({'b': 4})
print(my_dict)

1. {'a': 1, 'b': 2, 'c': 3, 'b': 4}
2. {'a': 1, 'b': 4, 'c': 3}
3. {'a': 1, 'b': 4}
4. {'b': 4}

Question 11: Insert the correct method to add a new key-value pair 'city': 'New York' to the dictionary person.

person = {'name': 'Alice', 'age': 30}
person.______('city', 'New York')

Question 12: How can you safely remove a key 'age' from the dictionary person without causing an error if the key doesn't exist?

1. person.remove('age')
2. person.pop('age')
3. person.delete('age')
4. person.pop('age', None)

Question 13: Which of the following methods can be used to remove a key from a dictionary? (Choose all that apply)

1. del my_dict['key']
2. my_dict.pop('key')
3. my_dict.remove('key')
4. my_dict.popitem()

Question 14: Arrange the steps to correctly update an existing key in a dictionary.

1. Define a dictionary person with keys 'name' and 'age'.
2. Update the value of 'age' to 31.
3. Print the updated dictionary.

Question 15: Complete the code to add a new key-value pair 'email': '[email protected]' to the dictionary person.

person = {'name': 'Alice', 'age': 30}
person['email'] = ______

Question 16: What will be the output of the following code?

my_dict = {'a': 1, 'b': 2}
value = my_dict.get('c', 10)
print(value)

1. None
2. 1
3. 10
4. KeyError

17. Insert the correct method to retrieve and remove the value associated with the key 'b' from the dictionary my_dict.

my_dict = {'a': 1, 'b': 2, 'c': 3}
value = my_dict.______('b')

Question 18: What is the result of the following code?

person = {'name': 'Alice', 'age': 30}
person.clear()
print(person)

1. {'name': 'Alice', 'age': 30}
2. {}
3. None
4. KeyError

Question 19: Which of the following can be used as keys in a Python dictionary? (Choose all that apply)

1. 'key'
2. 42
3. (1, 2)
4. [1, 2]

Question 20: Arrange the steps to safely retrieve a value from a dictionary or return a default value if the key does not exist.

1. Use the get() method with a default value.
2. Print the retrieved value.
3. Define a dictionary person with some key-value pairs.

Question 21: Complete the code to remove the last added key-value pair from the dictionary person.

person = {'name': 'Alice', 'age': 30, 'city': 'New York'}
person.______()

Question 22: What will be the output of the following code?

my_dict = {'x': 5, 'y': 10}
my_dict['z'] = 15
print(my_dict)

1. {'x': 5, 'y': 10}
2. {'x': 5, 'y': 10, 'z': 15}
3. {'z': 15}
4. {'x': 5, 'z': 15}

Question 23: Insert the correct code to check if the key 'age' exists in the dictionary person.

person = {'name': 'Alice', 'age': 30}
if 'age' in person:
    print('Age found')

Question 24: What will happen if you try to add a key to a dictionary that already exists?

1. The new key-value pair is added, and the old one is retained.
2. A KeyError is raised.
3. The old key-value pair is updated with the new value.
4. The program crashes.

Question 25: Which of the following methods can be used to access values in a dictionary? (Choose all that apply)

1. my_dict['key']
2. my_dict.get('key')
3. my_dict.value('key')
4. my_dict['key'] = 'value'