What is the output and why?

Question

a=[1,2,3,4]
b=a
a[2]=5
print(b)

Answer 1

That's because in Python the assignment points to same object.
So b is just another name for the object, which was called a.

If you want b to be another object, you need to modify the line b=a to
b = a.copy()

Then if you change an element in a, it's not affecting b

Answer 2

The output is [1,2,5,4]

a=[1,2,3,4] //here a[2]=3
b=a
a[2]=5 //Here replacing the value a[2]=3 to a[2]=5
print(b)//so the output is [1,2,5,4]

Answer 3

but we are printing b not a?