Question

multiply or divide the following measurements. be sure each answer you enter contains the correct number of significant digits.

78.1 cm × 35. cm = □ cm²

1. mol/l × 39. l = □ mol

814.8 mol ÷ 40.90 l = □ mol/l

Explanation:

First problem: \(78.1\ cm\times35\ cm\)

Step1: Perform the multiplication

$$78.1\times35 = 2733.5$$

Step2: Determine the number of significant digits

• \(78.1\) has 3 significant digits.
• \(35\) has 2 significant digits.
• The result should have 2 significant digits. So, \(2733.5\approx2.7\times10^{3}\)

Second problem: \(93\frac{mol}{L}\times39\ L\)

Step1: Perform the multiplication

$$93\times39=3627$$

Step2: Determine the number of significant digits

• \(93\) has 2 significant digits.
• \(39\) has 2 significant digits.
• The result should have 2 significant digits. So, \(3627\approx3.6\times 10^{3}\)

Third problem: \(814.8\ mol\div40.90\ L\)

Step1: Perform the division

$$814.8\div40.90=\frac{814.8}{40.90}\approx19.92176$$

Step2: Determine the number of significant digits

• \(814.8\) has 4 significant digits.
• \(40.90\) has 4 significant digits.
• The result should have 4 significant digits. So, \(19.92176\approx19.92\)

Answer:

\(2.7\times 10^{3}\ cm^{2}\), \(3.6\times 10^{3}\ mol\), \(19.92\frac{mol}{L}\)