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Two scientists use a massive, illuminated periodic table of elements as they discuss the element holmium in the Lawrence Hall of Science at the University of California, Berkeley. (Photo by ?? Ted Streshinsky/CORBIS/Corbis via Getty Images)

How many elements of the periodic table could we safely get rid of?

There are only a few elements essential to biology and modern technology, say our readers

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Close-up view of Black hole with Earth planet in deep space. Realistic science fiction art. Elements of this image furnished by NASA.; Shutterstock ID 2169109081; purchase_order: -; job: -; client: -; other:

If nothing can escape a black hole, how come gravity seems to?

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High five from a cute scruffy dog with a big smile! Cream wall background, shallow depth of field. Clever dog, the Bailey lightbox

Does left- and right-handedness exist in animals?

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Close up photo of peony flower bud with water drops at sunlight after rain in garden. Natural floral background. Gardening, spring season, growth concept.; Shutterstock ID 1726658389; purchase_order: -; job: -; client: -; other:

This week鈥檚 new questions

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Is there an equivalent of being ambidextrous for feet?

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Why do people scrunch up their eyes to see more clearly? Part 2

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This week鈥檚 new questions

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Row of tea cups with teabags falling motion inside on dark background - Colorful line of mugs with dropping flavored herb infusion - Close up image with black copy space; Shutterstock ID 551140699; purchase_order: -; job: -; client: -; other:

Why don鈥檛 coffee bags make very good coffee?

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Mandatory Credit: Photo by Karl Petersen/EPA-EFE/Shutterstock (9760878a) A general view shows an iceberg stranded near the village of Innaarsuit, in the Avannaata Municipality, northwestern Greenland, 12 July 2018 (issued 13 July 2018). The Avannaata Municipality was alarmed on 11 July, after a huge iceberg was grounded just outside the village of Innaarsuit. According to local media, police asked villagers who live closest to the water, to leave their houses over fears the iceberg could calve and affect the village with a tsunami. Iceberg grounded outside village in northwestern Greenland, Innaarsuit - 12 Jul 2018

What tipping points can we expect to see if we reverse global warming?

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KEXX6Y Mowing grass

This week鈥檚 new questions

Is there any difference between grass cut after the winter and grass cut regularly during the summer? What's the optimal ratio of frozen peas to water to minimise boiling time?

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What would the horizon look like on a disc-shaped planet? part 3

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This week鈥檚 new questions

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What is the advantage to walnuts and pecans of their convoluted form?

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Why do seals have such cute faces?

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