How to add random delays between the queries sent to Google to avoid getting blocked in python

First, Google probably are blocking you because they don't like it when you take too many of their resources. The best way to fix this is to slow it down, not delay randomly. Stick a 1 second wait after every request and you'll probably stop having problems.

That said:

from random import randint
from time import sleep

sleep(randint(10,100))

will sleep a random number of seconds (between 10 and 100).

Since you're not testing Google's speed, figure out some way to simulate it when doing your testing (as @bstpierre suggested in his comment). This should solve your problem and factor its variable response times out at the same time.

Best to use:

from numpy import random
from time import sleep

sleeptime = random.uniform(2, 4)
print("sleeping for:", sleeptime, "seconds")
sleep(sleeptime)
print("sleeping is over")

as a start and slowly decreasy range to see what works best (fastest).