Bananas are slightly radioactive.

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Bunches of ripe yellow bananas displayed at a market
Science

K-40

Bananas are slightly radioactive.

Bananas contain a small amount of naturally radioactive potassium-40 along with ordinary potassium. Their radiation dose is tiny, and normal banana consumption is not considered a radiation hazard.

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Water can boil and freeze at the same time.

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The Great Wall is difficult to distinguish from orbit with the naked eye.

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