Identify the hidden meaning behind this picture?

Can you find out what is missing?

1 3 5
2 4 ?

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

What's the only room from which no one can enter or leave

There are hundred red gems and hundred blue gems. The blue gems are priceless while the red gems equal wastage. You have two sacks one labeled Heads and the other Tails. You have to distribute the gems as you want in the two sacks. Then a coin will be flipped and you will be asked to pick up a gem randomly from the corresponding sacks.

How will you distribute the gems between the sacks so that the odds of picking a Blue gem are maximum?

There is a jar in which there are two types of candies.
20 blueberries and 16 strawberries. You perform the following steps:
1) You take out two candies.
2) If the two candies are of the same flavour, you add a blueberry one otherwise, you add the strawberry one.

You repeat these two steps till there is just one candy remaining in the jar. Which flavoured candy will be left?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

What word begins and ends with an E, but has only one letter?

"That Restaurant always remains crowded. This is the reason why nobody goes there".

Can you find a flaw in this statement?

I am a five-letter word under you,
Remove the first letter and I am above you,
Remove the second as well and I am around you.

Who am I?

If an electric train is travelling south, then which way is the smoke going?