What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

A large water tank has two inlet pipes (a large one and a small one) and one outlet pipe. It takes 3 hours to fill the tank with the large inlet pipe. On the other hand, it takes 6 hours to fill the tank with the small inlet pipe. The outlet pipe allows the full tank to be emptied in 9 hours.

What fraction of the tank (initially empty) will be filled in 0.64 hours if all three pipes are in operation? Give your answer to two decimal places (e.g., 0.25, 0.5, or 0.75).

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?

1 rabbit saw 9 elephants while going to the river. Every elephant saw 3 monkeys going toward the river. Each monkey had 1 parrot in each hand. How many animals are going towards the river?

There were three women in all the swimming costumes!
One was happy and the other two were sad!
The happy one was crying and the sad ones were smiling.
Why was this?

The answer I give is yes, but what I mean is no. What was the question?

If,

6 / 7 = 2
3 / 9 = 7
8 / 2 = 6

Then

4 / 5 = ?

Women do it once a year after they turn 19 but men get to do it only once in a lifetime. What is it?