When can we add 2 to 11 and get 1 as the correct answer?

What does below rebus means ?

Can you name four days which start with the letter 'T'?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day

Two boys were admitted to a school. When the headmaster asks them about their parents, they tell him that they have same parents (father and mother). On further inquiry, it turns out that they both share the same date for their birthday.

"Are you twins," ask the headmaster.
"No," replies the boys.

Is it possible?

If two fifty-foot ropes are suspended from a forty-foot ceiling that is twenty feet apart, how much rope will you be able to steal if you have a knife?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

A man dies of old age on his 25 birthday. How is this possible?