Which of the following methods can eliminate system errors?
A. Calibrate measuring instruments.
B. Improve measurement methods.
Change the test temperature.
D. Run a controlled experiment.
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Which of the following statements about significant figures is incorrect?
A. Significant figure refers to the number that can be actually measured in the analysis work.
B. The number zero does not affect the number of significant figures.
C. Significant figures reflect the accuracy of the measurement.
D. The last digit of significant figures is suspicious.
The following statement about the rules of number arithmetic is wrong?
A. When performing addition, usually the number of digits of the data is rounded reasonably first, and then the calculation is performed.
B. During subtraction, the number of digits after the decimal point reserved in the final calculation result should be based on the data with the least number of digits after the decimal point.
C. In the multiplication operation, the number of digits reserved in the calculation result depends on the number with the least number of digits after the decimal point.
D. In the division operation, the number of digits reserved for the calculation result depends on the number with the least significant number of digits.
After keeping 4 significant figures, which of the following numbers expressed in exponential form is wrong?
A. –0.024000 should be expressed as –2.400×10–2.
B. 374500 should be expressed as 3.745×105.
C. 0.000957830 should be expressed as 9.578×10–4.
D. 200.245700 should be expressed as 2.003×102.
Which of the following statements about random errors is incorrect?
A. Random error is caused by many unmeasurable errors that can affect the measurement result.
B. Random error is always too large or too small.
C. Random error conforms to normal distribution.
D. Random errors not only affect the accuracy of the measurement results, but also significantly affect the precision of the measurement results.
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