How Clever Are You?

Correct answer: Nitrogen Your first instinct might have been to say oxygen, but in fact air only contains 20% oxygen, whereas nitrogen makes up 78% of the air we breathe, along with 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.

Correct answer: Crocodile dung. The Kuhn gynaecological papyrus, written in around 1800BC, is one of the earliest descriptions of contraception. It describes using a clump of crocodile dung as a pessary before sex to prevent sperm entering the womb.

Correct answer: Chickens This surprisingly common phobia can also include dead chickens and eggs. It takes its name from the Greek alektor, meaning a rooster.

Correct answer: A bloat of hippos It's also OK to call them a pod, or even a school. But not a shoal.

Correct answer: It's changed colour. Lady Liberty is made from copper. She was a traditional burnished red-orange at first, but the copper reacted with air and moisture and developed a pale green outer layer called a patina.

Correct answer: Because of the tilt of the Earth's axis All season fluctuations are due to the fact that our planet is tilted on its axis. The Earth travels in a loop around the sun each year. Summer happens in the hemisphere tilted towards the sun, and winter happens in the hemisphere tilted away from the sun.

Correct answer: Burnt steak and hot metal Astronauts returning from a spacewalk have reported smells of “seared steak” or “hot metal”. According to chemist Steve Pearce, the smell is "caused by high-energy vibrations in particles brought back inside which mix with the air."

Correct answer: At your hand It's the official medical term for the back of your hand.

Correct answer: The Dry Valleys in Antarctica The Atacama desert is the driest nonpolar location in the world, but the absolute driest location is the Dry Valleys, a 4,800-square-kilometre region in Antarctica that has seen no rain for nearly 2 million years. It's considered to be the place on Earth that's most like Mars.

Correct answer: He was looking for a westward route to Asia Christopher Columbus was determined to find a direct water-based trading route west from Europe to Asia, but he never did. Instead, he accidentally stumbled upon the Americas, changing the course of world history forever.