Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

You are on your way to visit your Friend, who lives at the end of the hill. It is his birthday, and you want to give him the cakes you have made. Between your house and his house, you have to cross 5 bridges, and as it goes in the land of make believe, there is a troll under every bridge! Each troll, quite rightly, insists that you pay a troll toll. Before you can cross their bridge, you have to give them half of the cakes you are carrying, but as they are kind trolls, they each give you back a single cake. How many cakes do you have to leave home to make sure that you arrive at a friend's house with exactly two

What can you hold in your right hand, but never in your left hand?

What is next number in the pattern below:

131 517 192 123 ?

In the given picture, you can find two letters missing. When two particular letters are placed in the missing spots, you get an eight-letter word while reading in the anti-clockwise direction. Can you find out the missing letters and the missing word eventually?

Imagine a box with two cogwheels, one big with 24 teeth and one small with 8 teeth. The big one is firmly attached to the center of the box which means it does not turn or move while the small one rotates around the big one.

How many times do you think that the smaller wheel will turn compared to the box when it turns once around the big one?

What is the fastest way to double your money?

What brings you down but never up?

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