Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

Can you find out which options fits best with the missing column?

What does this mean?

CCCCCCC

When it is alive we sing, when it is dead we clap our hands. What is it?

Before the start of the car race, John and Jacob have the same amount of fuel in their car. With this fuel, John can drive for 4 hours while Jacob can drive five hours.
After a time they realize that the amount of fuel left in John's car is 1/4th of the fuel in Jacob's.

For how long they are racing?

How is the moon similar to a dollar?

Which Burger Is Different in below image?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

A girl was sitting in her hotel room when she heard a knock on the door. She opened the door and found that a man was standing outside.
The man said, "Oh! I am really sorry, I thought this was my room."
He then walked through the corridor to the elevator. The girl did not know the man. She closed her door and called security asking them to apprehend the man.
What made her suspicious of that man? He might have been genuinely mistaken.

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?