Question

count the significant digits in each of these measurements:

measurement	number of significant digits
90200. kg
0.004300 j
$-6.0 \times 10^{-1}$ kj/mol

Explanation:

For \( 7.9 \times 10^{-1} \) mL:

Step1: Recall significant digit rules for scientific notation. In \( a \times 10^n \), the significant digits are in \( a \).

Here, \( a = 7.9 \), so count the digits in \( 7.9 \).

Step2: Count digits in 7.9. There are 2 digits (7 and 9).

Step1: Recall rules for trailing decimals and non - zero digits. A decimal at the end (like in 90200.) means the trailing zeros are significant. Also, non - zero digits (9, 2) and the zeros between non - zero digits (the zero between 9 and 2) are significant.

Step2: Count the significant digits. The number is 9 (non - zero), 0 (between 9 and 2), 2 (non - zero), 0 (trailing, significant because of the decimal), 0 (trailing, significant because of the decimal). So 9, 0, 2, 0, 0. That's 5 digits.

Step1: Recall rules for leading and trailing zeros. Leading zeros (the three zeros before 4) are not significant. Non - zero digits (4, 3) and trailing zeros (the two zeros after 3) are significant.

Step2: Count the significant digits. 4, 3, 0, 0. That's 4 digits.

Answer:

2

For 90200. kg: