I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

Solve the mathematical equation in the picture below.

Which is heavier: a ton of bricks or a ton of feathers?

Two friends were stuck in a cottage. They had nothing to do and thus they started playing cards. Suddenly the power went off and Friend 1 inverted the position of 15 cards in the normal deck of 52 cards and shuffled it. Now he asked Friend 2 to divide the cards into two piles (need not be equal) with equal number of cards facing up. The room was quite dark and Friend 2 could not see the cards. He thinks for a while and then divides the cards in two piles.

On checking, the count of cards facing up is same in both the piles. How could Friend 2 have done it ?

A sea diver is a real show-off. He showed everyone that he can hold his breath underwater for 15 minutes.

I went to the diver and told him that I can be underwater for double the time i.e 30 minutes.
He responded that he will give me 100$ if I would be able to do it. I won 100$.

What did I do?

What is red and smells like blue paint?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

I am first found in caves, now prolific online; I am a depiction, a drawing, a symbol, or sign. I will convey whichever mood you could wish; or for that matter, a fist, flask, or fish. What am I?

Count the number of balls in picture below:

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?