1.
# one possibility
answer = raw_input("Enter a number: ")
num = float(answer)
print num

# a slightly more concise version
num = float(raw_input("Enter a number: "))
print num

2.
a. True
b. True
c. True
d. True
e. True
f. False
g. False

3.
def different(a, b):
    return a != b

Note the following does the same thing, but is NOT as good:

def different(a, b):
    if a == b:
        return False
    else:
        return True

(or other ways with an if statement).  Notice that the top definition is MUCH
more concise.