List comprehension iterates through range(3) [0,1,2], filters x>0 [1,2], and multiplies by 2: [2, 4].

isinstance() checks if an object is an instance of a class. 5 is an integer, so isinstance(5, int) returns True.

When y = x is executed, y gets the value 5. Later changing x to 10 does not affect y's value because integers are immutable.

The == operator compares values and types. 5 (integer) and '5' (string) are different types, so the result is False.

The count() method returns the number of occurrences of an element. 2 appears twice in the list.

range(1, 4) generates numbers from 1 to 3 (4 is excluded). The end=' ' parameter prints with space separator.

b has a default value of 5. When func(3) is called, a=3 and b=5 (default), so return 3+5=8.

The 'in' operator checks for key existence in a dictionary. has_key() was removed in Python 3.

Negative indexing starts from the end. s[-1] gives the last character 'n'. s = 'Python' has characters indexed from 0 to 5.

The floor division operator (//) returns the quotient without decimal places. 10 // 3 = 3.