It is always ahead of me yet I can never see it. What is it?

What number comes next in this sequence:
7 8 5 5 3 4 4 _

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

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

A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

How many triangles are there in the picture below?

If Rajina's daughter is my daughter's mom, who am I to Rajina?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?