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

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

Can you count the number of squares in the given picture?

If an earthquake is 1 point higher on the Richter Scale than another earthquake which is actually 10 times stronger, how much stronger would an earthquake be if it was just half a point higher on the Richter scale?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

I am a ten letters word
The first four letters have the power to rule,
Next, four-letter can be eaten.
The next three-letter represents a lady.
I can fly as well

what am I looking for?

Before Balboa discovered the Pacific Ocean, which was the largest ocean before that?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Which of the eight images will fill the missing image in the puzzle below?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?