Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

There are three boxes. One is labeled "APPLES" another is labeled "ORANGES". The last one is labeled "APPLES AND ORANGES". You know that each is labeled incorrectly. You may ask me to pick one fruit from one box which you choose.

How can you label the boxes correctly?

How many Watermelons are there in the below picture?

Can you name any English verb that becomes its past tense by simply rearranging the alphabets ?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?