Question

count the significant digits in each of these measurements:

measurement number of
significant digits

4.2 × 10^{-3} ml

1. kg

0.004200 j

-4.0 × 10^{-3} kj/mol

Explanation:

Step1: Count significant digits for \(4.2\times10^{-3}\text{ mL}\)

Non - zero digits are significant. Here, \(4\) and \(2\) are non - zero.

Step2: Count significant digits for \(13300.\text{ kg}\)

Trailing zeros in a number with a decimal are significant. \(1\), \(3\), \(3\), \(0\), \(0\) (the decimal makes the trailing zeros significant).

Step3: Count significant digits for \(0.004200\text{ J}\)

Leading zeros are not significant. Non - zero digits (\(4\), \(2\)) and trailing zeros after non - zero digits (\(0\), \(0\)) are significant.

Step4: Count significant digits for \(-4.0\times 10^{-3}\text{ kJ/mol}\)

Non - zero digit (\(4\)) and the zero after the decimal is significant.

Answer:

measurement	number of significant digits
\(13300.\text{ kg}\)	\(5\)
\(0.004200\text{ J}\)	\(4\)
\(-4.0\times 10^{-3}\text{ kJ/mol}\)	\(2\)