Before Mount Everest was discovered, what was the highest mountain in the world?

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 white when I am dirty, and black when I am clean. What am I?

While going to your grandmother's house, you counted Twenty houses on the right side. While returning back to your home, you counted Twenty houses on the left side.

How many houses are there between your home and your grandmother's home?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

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

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

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

Cristina leaves home and then she makes exactly 3 left turns and returns home where she found 2 girls wearing the mask.

Who are these two masked girls?