Multiple Choice
Why do scientists use the International System of Units (SI) as a common system of measurement?
1. Intro to General Chemistry
SI Units
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Which of the following numbers are exact?
A
4 apples
B
1000 m = 1 km
C
4.2 m
D
both the first and second choices
E
both the first and third choices
F
both the second and third choices
Verified step by step guidance1
Understand the concept of exact numbers: Exact numbers are those that are counted or defined, rather than measured. They have an infinite number of significant figures.
Examine the first choice: '4 apples'. This is a counted number, as you can count the apples directly. Therefore, it is an exact number.
Examine the second choice: '1000 m = 1 km'. This is a defined relationship between meters and kilometers, making it an exact number.
Examine the third choice: '4.2 m'. This is a measured value, which means it is not exact. Measured values have a limited number of significant figures.
Determine which choices are exact: Based on the analysis, both the first and second choices are exact numbers.
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