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

You have 10 balls with you. A friend of yours out of nowhere asks you to place those ten balls in five lines such that each of the lines has exactly 4 balls on them. He needs to check your intelligence. Prove him by doing the task.

One day Jenifer meets the Lion and the Tiger in the Forest of Forgetfulness. She knows that the Lion lies on Mondays, Tuesdays, and Wednesdays, and tells the truth on the other days of the week. The Tiger, on the other hand, lies on Thursdays, Fridays, and Saturdays, but tells the truth on the other days of the week. Now they make the following statements to Jenifer:

Lion: Yesterday was one of my lying days.

Tiger: Yesterday was one of my lying days too.

What day is it?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

Here is a mathematical expression that also secretly tells a movie name. What movie is that?

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

Which word is least like the others? Third, fourth, fifth, sixth, seventh, eighth, ninth?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

A man and a dog were going down the street. The man rode, yet walked. What was the dog’s name?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?