To express the given value $2.58 \times 10^{-23} \pm 2.63 \times 10^{-24}$ with the correct significance level, we need to adjust the precision of both the main value and the uncertainty to match the least precise figure.

Here's the breakdown:

• The main value is $2.58 \times 10^{-23}$ (with 3 significant figures).
• The uncertainty is $2.63 \times 10^{-24}$ (with 3 significant figures).

Since the uncertainty is the least precise number, we need to round the main value to the same number of significant figures as the uncertainty (3 significant figures).

Thus, the correctly expressed value would be:

$2.58 \times 10^{-23} \pm 2.63 \times 10^{-24}$

This is already expressed to the correct significant figures as both the main value and uncertainty have 3 significant figures.

Let me know if you'd like more details or have any further questions!

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Here are 5 related questions:

1. How do you determine the number of significant figures in a measurement?
2. What is the difference between absolute and relative uncertainty?
3. How do you round numbers to the correct number of significant figures?
4. What is the importance of maintaining consistent precision when reporting values?
5. How can uncertainty in measurements affect the interpretation of scientific data?

Tip: Always match the number of significant figures in your measurement to the least precise value in the calculation or measurement set.