1) як позначається активність радіоактивних ізотопів?2)як змінюються заряд та маса ядра під час бета - розпаду?3) знайдіть скільки відсотків радіоактивного препарату Йоду-131 з періодом піврозпаду 8 діб залишиться через 40 діб.

danced with the prince She at the palace

разность наименьшего четырехзначного числа и единицы уменьши в 9 раз.

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Mr and Mrs Young's small house was in a village, but their children's houses were in a town. Then Mr Young died. Mrs Young was eighty-five years old, and her children said to her, "Come and live in the town near us, Mother. Or come and live in one of our houses." But she said, "No, I'm not going to go to the town. I'm going to remain here." Her children were not happy. They said, "There are a lot of burglars here now. Maybe one of them will come into her house and take her money and her nice things." One Sunday one of her daughters went to Mrs Young's house. She saw a key on the ground at the side of the front door. "Mother!" she said, "You mustn't put your key there. That's the worst place. Burglars can see it and open the door!" Mrs Young smiled. "Try to open the door with the key," she said. Her daughter did this. The key made a lot of noise, but it did not open the door. Then Mrs Young said, "I hear the key in the lock, and then I get one of my brother's old guns, go out of the back door and creep up behind the burglars." 21