Question

a chemist needs to know the mass of a sample of potassium sulfate to 2 significant digits. she puts the sample on a digital scale. this is what the scale shows:
0 0 0 3 9.7 g
if this measurement is precise enough for the chemist, round it to 2 significant digits.
otherwise, press the
o solution\ button.
try again
your answer is wrong. the number of significant digits cant be determined.

Explanation:

Step1: Identify significant digits rules

Leading zeros are not significant. So, the number \(0.00397\) has three significant digits (\(3\), \(9\), \(7\)).

Step2: Round to 2 significant digits

Look at the third digit. The number is \(0.00397\). The first non - zero digit is \(3\) (first significant digit), the next digit is \(9\) (second significant digit), and the digit after \(9\) is \(7\) (\(7\gt5\)). When rounding \(0.00397\) to two significant digits, we round up the second significant digit. So, \(0.00397\approx0.0040\) (in decimal form) or \(4.0\times10^{- 3}\) (in scientific notation).

Answer:

\(4.0\times10^{-3}\text{ g}\)