Can you name an animal whose killing cannot be performed without spilling your own blood?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

Why is 6 afraid of 7?

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

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?

Solve below rebus puzzle?

You have a roll of cloth 1km long. You have a machine which cuts this roll into pieces of 10-meter-long cloth.

How long would it take for the machine to cut the roll if each cut took 4 secs?

Take away the whole and some still remain. What is it?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?