Question

8. A log is burning in a fireplace. If the amount of oxygen reaching the log is decreased, which of the
following statements is true? (1 point)
The reaction rate increases.
The reaction rate decreases.
The reaction rate remains the same.
The reaction rate only depends on the temperature.

Answer 1

9. Carbon-14 has a half-life of 5,730 years. If the age of an object older than 50,000 years cannot
be determined by radiocarbon dating, then: (1 point)
Carbon-14 levels in a sample are undetectable after approximately 11 half-lives.
Carbon-14 levels in a sample are undetectable after approximately 9 half-lives.
The half-life of Carbon-14 is too long to accurately date the object.
A radioisotope with a shorter half-life should be used.

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Answer 2

50.000/5730 is approximately 9 which is the number of half-lives. B is correct.

Answer 3

For number 8, the rate of burning decreases with a decrease in oxygen.