Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

There were two grandmothers and their two granddaughters.
There were two husbands and their two wives.
There were two fathers and their two daughters.
There were two mothers and their two sons.
There were two maidens and their two mothers.
There were two sisters and their two brothers.
Yet there are only six, who are buried here,
All are born legitimate and relationships clear.
How can this happen?

What is the coolest letter in the alphabet?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

There were five men at church, and it started raining while they were outside. The four that ran still got wet, but the one that was still stayed completely dry. Why did he stay dry?

What work can one never finish?

Why do Chinese men eat more rice than Japanese men do ?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

Replace the question mark with the correct number in below Picture:

What is the next number in this matchsticks series riddle?