Which number should replace the question mark?

John is the son of Jacob.
So,
Jacob is the_____of John's father?

Replace the question mark with the correct number in the below-given picture?

I have an eye but still cannot see.

Who am I?

John asked Jack, "The time right now is 7 pm. Can you tell me what will be the time 23, 999, 995 hours later ?"

While Bella does not know the answer, do you ?

Client Dempsey living in one of the East Coast states of the U.S. was talking to Landon Donovan, who was living in the West Coast state of the U.S.

Dempsey: What time is it?
Donovan: Wow, It is the same time here.

How is this possible?

What is black when you buy it, red when you use it, and gray when you throw it away?

Only Highly Attentive Can Spot The Ladder In This Library In 7 Seconds! Can You?

Solve the riddle below:

If a Chicken says, 'All chickens are liars" is the chicken telling the truth?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.