Can you identify if it's a murder or a suicide ?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?

What makes this number unique: 8,549,176,320?

Do You See It?

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?

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

You have two bottles of pills marked with labels A and B. The pills are identical. The doctor has asked you to take one A pill and one B pill daily. You cant take more or less than that.

While taking out the pills one day, you took out one pill from A and by mistake took out two from B. You have no idea which pill is which now.

You cant throw away the expensive pills. What will you do now?