What does below chemistry rebus means?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

A person was found dead on a big green land with no trees or buildings around. When the police arrived, they found a piece of rock lying next to him and the man was wearing clothes comprising of red, blue and yellow colours.

Can you tell who the person is and what was the cause of death?

There are three boxes which are labeled as Rs100, Rs150, and Rs200. One box contains two notes of Rs. 50. The second box contains one note of Rs50 and one note of Rs100 The third box contains two Rs. 100 notes. All boxes are labeled incorrectly.

What is the minimum number of boxes you must check in order to label all boxes correctly?

Find the missing number in the sequence below:

If two fifty-foot ropes are suspended from a forty-foot ceiling that is twenty feet apart, how much rope will you be able to steal if you have a knife?

When we see 2 but call 10?

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

Can you find the largest Three-digit number whose sum is 14 and whose square is less than 5,00,000?