Sets - General Questions

What is the output of the following code?

a = {1, 2, 3}
b = {2, 3, 4}
print(sorted(a & b), sorted(a | b))

Why can't a list be an element of a set?

What is the output of the following code?

print({1, 2}.isdisjoint({3, 4}))

What is the output of the following code?

print({1, 2} <= {1, 2, 3}, {1, 4} <= {1, 2, 3})

What is the output of the following code?

words = ['a', 'b', 'a', 'c', 'b']
print(len(set(words)))