What's the only room from which no one can enter or leave

If eleven plus two equals one, what does nine plus five equal?

In which direction should the missing arrow point?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

Suppose we lay down two cups in front of you. One of the cups is filled with tea and the other one with coffee. Now we ask you to take a spoonful of tea and mix it with the coffee. At this moment, the coffee cup has a mixture of tea and coffee. You have to take that mixture (spoonful) and add it back to the tea.

Can you now tell if the cup of coffee has more tea or the cup of tea has more coffee?

What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?

If you say my name, I will no longer exist. What am I?

What is the word or phrase?

Can you complete the sequence puzzle?

AR TA GE CA LE VI LI _

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?