What is in seasons, seconds, centuries and minutes but not in decades, years or days?

In the image below, can you find the value of an angle(y)

A Doctor always sneezes before the rain. Doctor sneezes, Will it rain?

A man is shown a portrait painting. He looks closely, then tells, “Brothers and sisters have I none, but that man’s father is my father’s son!” Who is the man in the portrait?

A cat had three kittens: Snophy, Topsy and Jorden. What was the mother's name?

What you cannot hold but it is yours?

By adding four matchsticks, can you divide the square shown in the picture into two equal parts?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

Name a key which is hardest to turn.