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.
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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.
Which of the calculation about significant figures is incorrect?
A. 0.03050 has 4 significant digits.
B. 12.050 has 5 significant digits.
C. pH = 5.25 has 3 significant digits.
D. 7.2×10–5 has 2 significant digits.
Which of the following statements about errors is wrong?
A. Uncalibrated instrument will cause errors
B. Impure reagents will cause measurement errors
C. System errors can be eliminated by improving test methods
D. Random errors can be eliminated by improving test methods
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