Last Puzzles (Hard Ten Boxes Interview Puzzle)

You have ten boxes and an electronic weighing machine. In those ten boxes, you have chocolates. Each chocolate weigh 20 grams. But in one box the chocolates are defective and each weigh 19 grams exactly. Now you can weigh in the electronic weighing machine but you can use that machine just once. How will you find out which box has the defected chocolates.

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