Question

count the significant digits in each of these measurements:
measurement number of significant digits

• 9.0 × 10⁻¹ kj/mol

1. kg

0.00900 j
1.4 × 10⁻¹ ml

Explanation:

Step1: Recall significant - digit rules

Non - zero digits are always significant. Zeros between non - zero digits are significant. Leading zeros (zeros before non - zero digits) are not significant. Trailing zeros in a number with a decimal point are significant.

Step2: Analyze $-9.0\times10^{-1}\text{ kJ/mol}$

The non - zero digit 9 and the zero after it (since there is a decimal point) are significant. So, there are 2 significant digits.

Step3: Analyze $7500.\text{ kg}$

The non - zero digits 7 and 5 are significant, and the two trailing zeros are significant because there is a decimal point. So, there are 4 significant digits.

Step4: Analyze $0.00900\text{ J}$

The leading zeros are not significant. The non - zero digit 9 and the two trailing zeros (because of the decimal point) are significant. So, there are 3 significant digits.

Step5: Analyze $1.4\times10^{-1}\text{ mL}$

The non - zero digits 1 and 4 are significant. So, there are 2 significant digits.

Answer:

• $-9.0\times10^{-1}\text{ kJ/mol}$: 2
• $7500.\text{ kg}$: 4
• $0.00900\text{ J}$: 3
• $1.4\times10^{-1}\text{ mL}$: 2