Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

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

What can you deduce from the following BrainBat?

CRY
LMKI

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?

Can you divide numbers from 1 to 9 (1 2 3 4 5 6 7 8 9) into two groups so that the sum of the numbers of each group is equal?

Note: 9 cannot be turned over to make it 6.

A bag contains 64 balls of eight different colours. There are eight of each colour (including red). What is the least number you would have to pick, without looking, to be sure of selecting 3 red balls?

How do you go from 98 to 720 using just one letter?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?