Can you fill the blank with the correct number?

6 30 870 756030 _____

When it is alive we sing, when it is dead we clap our hands. What is it?

What's the next in the series?

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

No one wants to have it, but if one got it, he does not want to lose it. What is It?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

On a special event at the prison, 5 prisoners John, Jacob, Krist, Tang, and Dang given a chance to go to a sauna and can bring one thing with them.

Following are the things that the prisoners bring with them.
John: A soda
Jacob: Thermos
Krist: Book named "How to kill"
Tang: A Walkman
Dang: Harmonica

Since it is a Sauna, no one can see each other. After a while When the steam is switched, Tang was found dead and there was blood all around.
J Bond was called and he instantly come to know who can be the murderer. How?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

There is a unique number which when multiplied by any number from 1 to 6, we will get the new number that contains the same digits only.

Can you find that number?

You have 10 balls with you. A friend of yours out of nowhere asks you to place those ten balls in five lines such that each of the lines has exactly 4 balls on them. He needs to check your intelligence. Prove him by doing the task.