There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

It belongs to you, but other people use it more than you do. What is it?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?