It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

How many triangles are there in the picture below?

If we tie a Sheep to one peg, a circled grass is been eaten by the Sheep. If we tie the Sheep to two pegs with a circle on its neck, then an eclipse is eaten out of the grass by the Sheep. If we want an eclipse then we put two pegs and then put a rope in between them and the other end of the rope is tied up on the Sheep's neck.

How should we tie the peg and the Sheep so that a square is eaten out from the garden grass? We only have one Sheep rope and the peg and the rings.

What is the centre of gravity?

In the figure, you can see nine stars. What you have to do is connect all of them by using just four line and without lifting your hand i.e. in a continuous flow.

How many Watermelons are there in the below picture?

What is next number in the pattern below:

131 517 192 123 ?

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

Find out which of the given views in the picture is accurately the top view of the given pyramid.