Boron là nguyên tố có nhiều tác dụng đối với cơ thể người như: làm lành vết thương, điều hoà nội tiết sinh dục, chống viêm khớp,... Do ngọn lửa cháy có màu lục đặc biệt nên boron vô định hình được dùng làm pháo hoa. Boron có hai đồng vị là 10B và 11B, nguyên tử khối trung bình là 10,81. Tính phần trăm số nguyên tử mỗi đồng vị của boron.
1. % 10B = %.
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Ta có phương trình:
$\frac{10x + 11(100-x)}{100} = 10.81$
$10x + 1100 - 11x = 1081$
$-x = -19$
$x = 19$
Vậy, phần trăm số nguyên tử của 10B là 19% và phần trăm số nguyên tử của 11B là 100% - 19% = 81%.
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Xác định ý đúng: Việc phân chia tài nguyên thiên nhiên thành tài nguyên đất, nước,khí hậu, sinh vật, khoáng sản được cho là sự phân loại dựa vào?
