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Hard/Difficult Riddles

Medium Health

How many skin cells shed every minute?

Medium Health

What is the heaviest internal organ?

Medium Health

Who created the first polio vaccines?

Medium Health

How much blood is in the human body?

Medium Water

World’s largest Hydroelectric Power Plant?

Medium Water

What is the deepest part of the ocean?

Medium Water

How much water do Americans use daily?

Medium Water

What provides 90% of atmospheric water?

Medium Water

How much of Earth’s water is saltwater?

Medium Water

Where is most freshwater located?

Medium Water

How much water is stored in oceans?

Medium Animals

How many bones are in a giraffe’s neck?

Medium Animals

What do you call a group of flamingos?

Medium Animals

How long can beavers hold their breath?

Medium Animals

What are sea monkeys?

Medium Animals

What animal kills the most humans each year?

Medium Animals

Largest mammal in North America?

Medium Animals

Which animal did Australia go to “war” with?

Medium Space

Average distance between Earth and the moon?

Medium Space

Where does the asteroid belt lie?

Medium Space

Who was the first American woman in space?

Medium Space

How long for the ISS to orbit the Earth?

Medium Space

What is the coldest planet in our solar system?

Medium Space

When was our solar system formed?

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