What goes up but never comes down?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

Below rebus represent famous DiCaprio movie. Can you name it?

You’ll find me on Mercury, Earth, Mars, Jupiter, Saturn, and Uranus. But never Neptune, or Venus. What am I?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

A boy collects white seashells from the sea and brings them home every night. When he has enough of them, he decides to sell them to a trader.

The trader is ready to buy the shells and he asks the boy about the quantity. At this, the boy starts calculating. He has a giant box that contains 3 mini boxes. Two of them have another mini box inside. If the giant box can hold 50 shells, how many brown shells can he sell to the trader?

What number should come in place of the question mark below?

Role Action
Block Prevents the target player from acting
Redirect Change target player target.
Save Protects the target player from death.
Seer Sees all actions that occurred
Murderer Kills the target player

The following five players are playing:

Andy
Brian
Chris
Daniel
Fred

You are Andy the Seer and you saw the following things:
a) Brian was redirected to Chris.
b) Chris was blocked.
c) Daniel was killed.

Who is the murderer then?

What building has the most stories?