What is always in front of you but can’t be seen?

People are waiting in line to board a 100-seat aeroplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise, they will choose an open seat at random to sit in. The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?

I have feet, but no legs. Which animal Am I?

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

What word begins and ends with an E, but has only one letter?

Can you count the number of triangles in the given figure?

What has 13 hearts but no other organs?

Why is it very easy to weigh a fish?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

A frog is at the bottom of a 30-meter well. Each day he summons enough energy for one 3-meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?