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

The day before yesterday I was 25 and the next year I will be 28. This is true only one day in a year. What day is my birthday?

In the picture that is attached with this question, you can find a square which comprises of four little squares inside it. Consider this square to be made with matchsticks. You have to remove two matchsticks such that only two squares remain instead of five.How will you do it ?

You know three triplets: Frank John and Wayne (need to return your money). Frank always tells the truth while John and Wayne always lie. You meet one of them on the road and can ask him a three-word question.
Which question, will you ask?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

By moving exactly three matchsticks can you make the below equation true.It can be solved by 3 ways.

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

I look flat, but I am deep. Hidden realms I shelter. Lives I take, but the food I offer. At times I am beautiful. I can be calm, angry, and turbulent. I have no heart but offer pleasure as well as death. No man can own me, yet I encompass what all men must have. What am I?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

During which month do people sleep the least?