What has 13 hearts but no other organs?

John was born on March 5, 1970, in Delhi, India. Jacob was born 25 days before John. The year when they took birth, Republic Day fell on Monday.

Can you find out on what day was Jacob born?

I can sizzle like bacon,
I am made with an egg,
I have plenty of backbone, but lack a good leg,
I peel layers like onions, but still remain whole,
I can be long, like a flagpole, yet fit in a hole.

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?

What begins with T, ends with T, and has T in it?

John can fit six large chocolate boxes or nine small chocolate boxes into a carton. How many cartons will he require to put sixty-six chocolate boxes into?

You can find some missing letters in the picture. By placing two particular letters in the spaces, you can form a nine lettered word beginning from one of the corners and going clockwise direction to the middle. Can you find out the letters and the word?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

What has a bottom at the top?

Which digit occurred maximum times between the number 1 and 1000?