Here are five examples demonstrating how to check if a key exists in a dictionary:

1. Using the in keyword:

my_dict = {'apple': 3, 'banana': 5, 'orange': 2}

if 'apple' in my_dict:
    print("The key 'apple' exists in the dictionary.")
else:
    print("The key 'apple' does not exist in the dictionary.")

2. Using the get() method:

my_dict = {'apple': 3, 'banana': 5, 'orange': 2}

if my_dict.get('apple') is not None:
    print("The key 'apple' exists in the dictionary.")
else:
    print("The key 'apple' does not exist in the dictionary.")

3. Using exception handling (try-except):

my_dict = {'apple': 3, 'banana': 5, 'orange': 2}

try:
    value = my_dict['apple']
    print("The key 'apple' exists in the dictionary.")
except KeyError:
    print("The key 'apple' does not exist in the dictionary.")

4. Using the keys() method:

my_dict = {'apple': 3, 'banana': 5, 'orange': 2}

if 'apple' in my_dict.keys():
    print("The key 'apple' exists in the dictionary.")
else:
    print("The key 'apple' does not exist in the dictionary.")

5. Using the in operator with a for loop:

my_dict = {'apple': 3, 'banana': 5, 'orange': 2}

for key in my_dict:
    if key == 'apple':
        print("The key 'apple' exists in the dictionary.")
        break
else:
    print("The key 'apple' does not exist in the dictionary.")

All these examples achieve the same result of checking if the key 'apple' exists in the dictionary my_dict.