To determine which set of numbers is arranged in descending order, we first need to compare the numbers based on their values. The numbers are in scientific notation, so we start by considering the exponent part (the power of 10) first.
- 7 × 10^−30
- 7.2 × 10^−25
- 7.2 × 10^−30
- 7.6 × 10^−25
Exponents from largest to smallest:
- 10^−25 (this will affect 7.2 × 10^−25 and 7.6 × 10^−25)
- 10^−30 (this will affect 7 × 10^−30 and 7.2 × 10^−30)
Now, we can summarize the numbers based on their exponents:
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For exponent 10^−25:
- 7.6 × 10^−25 (largest)
- 7.2 × 10^−25 (smaller)
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For exponent 10^−30:
- 7.2 × 10^−30 (larger)
- 7 × 10^−30 (smallest)
Now, we can evaluate the given sets:
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7 × 10^−30, 7.2 × 10^−25, 7.2 × 10^−30, 7.6 × 10^−25
- This is NOT in descending order.
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7.2 × 10^−30, 7 × 10^−30, 7.6 × 10^−25, 7.2 × 10^−25
- This is NOT in descending order.
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7.6 × 10^−25, 7.2 × 10^−25, 7.2 × 10^−30, 7 × 10^−30
- This is in descending order.
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7.6 × 10^−25, 7.2 × 10^−30, 7.2 × 10^−25, 7 × 10^−30
- This is NOT in descending order.
Conclusion: The correct answer is: 7.6 × 10^−25, 7.2 × 10^−25, 7.2 × 10^−30, 7 × 10^−30.