Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

You are offered an opportunity to win a fortune. There are 100 precious black stones and 100 unworthy white stones. There are two different sacks labelled as "Heads" and "Tails". You can distribute the stones as you wish. Then a coin will be flipped. Then you will have to choose a stone from the corresponding sack. If you pick up a black stone, all the fortune of black stones is yours but if you pick up white, you get nothing.

How will you distribute the stones so that you can maximize your chances of winning?

If,

A = 1

B = 2

C = 3

...

...

Z = 26.

Based on above rule, you need to find an eleven letter word whose letter sum is equal to 52.

Assume the given figure to be a delicious doughnut. Yes, now you can concentrate more on the puzzle. So you have this delicious doughnut in your refrigerator when your friends come knocking at the door. There are eight of them. Now you have to make three cuts in this doughnut so that each one of you nine people can enjoy a piece of it. Neither you nor your friends would mind the size of their piece as long as they are getting it. How will you do it?

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?

In the following picture, E is going to slide the object down and as per the terrain and the physics, the round object is going to travel all the way till the end. Now, can you analyze who all people will die when it happens?

Name a key which is hardest to turn.

Can anyone tell me a word in the English dictionary which has a silent 'z'?