what does this picture(rebus) riddle means ?

What is always in front of you but can’t be seen?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

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?

How many letters are in the alphabet?

Can you solve the below geography rebus by decoding the below rebus ?

Can you place six X (crosses) in below board without making three in a row in any way ?

If you had an infinite supply of water and 5-quart and 3-quart pails, how would you measure exactly 4 quarts? What is the least number of steps you need?

What is the next number in this series?

4,12,84,3612....

Find out the missing number in the picture attached: