The more of this there is, the less you see. What is it?

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?

A wooden log balances equally on the scales when weighed with three-quarters of a pound and three-quarters of a wooden log.

Can you calculate the weight of the entire wooden log?

Count The number of F's in the paragraph below:

"FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS"

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

What is more useful when it is broken?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

I am beautiful, up in the sky. I am magical, yet I cannot fly. To people I bring luck, and to some people, riches. The boy at my end does whatever he wishes. What am I?

I’m tall when I’m young, and I’m short when I’m old. What am I?