Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

Replace the question mark with the number below given a simple math problem.

What does this rebus picture identify?

I have branches, but no fruit, trunk or leaves. What am I?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

What word is represented by this rebus?

Assume the given figure to be a delicious doughnut. Yes, now you can concentrate more on the puzzle. So you have this delicious doughnut in your refrigerator when your friends come knocking at the door. There are eight of them. Now you have to make three cuts in this doughnut so that each one of you nine people can enjoy a piece of it. Neither you nor your friends would mind the size of their piece as long as they are getting it. How will you do it?

Solve the equation in the image by looking at the pattern closely.

I am lying and I always lie. Tell me whether I am lying or telling the truth.