What has many keys but can’t open a single lock?

A Shopkeeper collects 71 rupees in the form of 20 paisa and 25 paisa.
He collects a total of 324 coins.

Can you tell me how many number of 20-paisa and 25-paisa he got?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

I add 5 to 9 and get 2. The answer is correct, so what am I?

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

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

What has 88 keys?

I have an eye but still cannot see.

Who am I?

Given that

(78)^9 = 6
And (69)^4 = 11

Can you find out

(99)^2 =?

(Note: This is Logical, not Mathematical)

What jumps when it walks and sits when it stands?