What colour is octopus’s blood and how heavy is the sky? The kids’ quiz

1. Matteo, 11, asks: what colour is octopus’s blood?

   1. Green

   2. Blue

   3. Red

   4. Transparent

2. Bertie, 4, asks: how heavy is the sky?

   1. It depends on how much pollution there is

   2. The sky is weightless and has no mass

   3. The mass of the sky is more than 5 quadrillion tonnes – the same weight as roughly 100 million Great Walls of China

   4. 100 kilograms – about the same weight as an average washing machine

3. Alex, 10, asks: why do we have nightmares?

   1. Lack of sleep

   2. Stress

   3. A frightening experience

   4. All of the above

4. Isabella, 5, asks: how do we make electricity from geysers? How does it travel to our house?

   1. Steam and hot water from geysers are used to make electricity, and transported through power lines

   2. Water creates energy that’s sent via radio waves

   3. Fish in geysers swim on a treadmill, creating energy that’s transported in trucks

   4. Geyser water is electrically charged, and is transported on bikes

5. Nathan, 4, asks: how are we able to see through glass?

   1. Pixies cast a magic spell

   2. We have X-ray vision

   3. Glass is technically a liquid, so you can always see through it

   4. Glass does not reflect or absorb much light – so it’s transparent

Solutions

1:B - An octopus has bluish blood due to a copper-based protein called haemocyanin. It can transport oxygen in cold conditions., 2:C - It’s a complicated question! Physicists talk about the mass of air rather than its weight. According to Britannica, the total mass of Earth’s atmosphere is about 5.5 quadrillion tonnes (that’s 5.5 million billion tonnes). The Great Wall of China is estimated to weigh roughly 50 million tonnes! , 3:D - Lack of sleep, stress and experiencing something scary can all cause a nightmare. They usually happen just before you wake up, when your brain is very active. They feel very real, but they are tricks of your imagination, and will vanish when you wake up., 4:A - A geyser is a natural pool of hot water that shoots water and steam into the air. The steam is used to drive a turbine, a machine that converts it into electrical energy, which is sent through power cables., 5:D - Glass does not reflect or absorb much light, which allows light rays to pass through it, and this means we can see through it.

Scores

1. 5 and above.

2. 4 and above.

3. 3 and above.

4. 2 and above.

5. 0 and above.

6. 1 and above.