Q 01/05

Which food, properly stored, essentially never spoils, with samples from ancient tombs still edible?

A) Olive oil

B) Hard cheese

C) Dried rice

D) Honey

Answer · why

D) Honey

Its high sugar concentration and acidity stop most microbes growing, which is why archaeologists have found jars of it still edible after millennia.

Q 02/05

On which planet does a single day (one rotation) last longer than its year?

A) Mercury

B) Venus

C) Mars

D) Jupiter

Answer · why

B) Venus

It takes 243 Earth days to spin once but only about 225 to circle the Sun, and it spins the wrong way too.

Q 03/05

Which everyday fruit is radioactive enough to serve as an informal unit of radiation dose?

A) Apple

B) Orange

C) Banana

D) Grape

Answer · why

C) Banana

The 'banana equivalent dose' comes from naturally occurring potassium-40, and eating one is worth roughly 0.1 microsieverts.

Q 04/05

The air around a lightning bolt heats to roughly what temperature?

A) 300 °C

B) 3,000 °C

C) 10,000 °C

D) 30,000 °C

Answer · why

D) 30,000 °C

That is about five times hotter than the surface of the Sun, and the sudden expansion of that air is what we hear as thunder.

Q 05/05

On a hot day, the top of the Eiffel Tower can lean away from the sun by up to how much?

A) 1 cm

B) 5 cm

C) 10 cm

D) 18 cm

Answer · why

D) 18 cm

The metal on the sunny side expands more than the shaded side, so the whole tower bends slightly away from the heat.