Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

A father's child, a mother's child, yet no one's son.

Who am I?

Find the smallest sentence with all the English alphabet.

What does the below mathematical rebus mean?

What work can one never finish?

A time long back, there lived a king who ruled the great kingdom of Trojan House. As a part of the renovation of the kingdom to meet future security needs, he asked his chief architect to lay down a new play in a manner that all of his 10 castles are connected through five straight walls and each wall must connect four castles together. He also asked the architect that at least one of his castles should be protected with walls. The architect could not come up with any solution that served all of King's choices, but he suggested the best plan that you can see in the picture below. Can you find a better solution to serve the king's demand?

It spends most of its day eating white, but when it’s quick enough, it gets to eat fruit and sometimes some blue things. It’s in a dark room, where the walls are blue, it runs from a ghost that roams the halls and haunts it all the time. What is it?

In the addition below, all digits have been replaced by letters. Equal letters represent equal digits and different letters represent different digits.
ABCABA
BBDCAA
ABEABB
ABDBAA
------- +
AAFGBDH
What does the complete addition look like in digits?

Give it food and it will live; give it water and it will die.

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?