If you’ve got me, you want to share me; if you share me, you haven’t kept me. What am I?

I have teeth but i don't bite. Who Am I ?

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

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

How can you leave a room with two legs and return with six legs?

Can you name some countries which do not have the alphabet 'A' in them?

Which of the following words don't belong in the group and why?
CORSET, COSTER, SECTOR, ESCORT, COURTS