Chapter 9, Problem 126A

Interpretation Introduction

(a)

Interpretation:

The given problem needs to be solved in scientific notation and rounded off to the correct number of significant figure.

$\left(5.31\times {10}^{-2}\text{cm}\right)\times \left(2.46\times {10}^5\text{cm}\right)$

Concept introduction:

To multiply or divide numbers in scientific notation, multiply or divide the coefficients and then add or subtract the exponents, respectively.

Answer to Problem 126A

$1.31\times {10}^4{\text{cm}}^2$.

Explanation of Solution

Compute the following calculation.

$\begin{array}{c}\left(5.31\times {10}^{-2}\text{cm}\right)\times \left(2.46\times {10}^5\text{cm}\right)=13.0626\times {10}^3{\text{cm}}^2\\ =1.31\times {10}^4{\text{cm}}^2\end{array}$

Interpretation Introduction

(b)

Interpretation:

The given problem needs to be solved in scientific notation and rounded off to the correct number of significant figure.

$\left(4.42\times {10}^{-2}\text{g}\right)÷\left(3.21\times {10}^{-3}\text{g}\right)$

Concept introduction:

To multiply or divide numbers in scientific notation, multiply or divide the coefficients and then add or subtract the exponents, respectively.

Answer to Problem 126A

Round off to the correct number is $2\times {10}^1$.

Explanation of Solution

Compute the following calculation.

$\begin{array}{c}\left(6.42\times {10}^{-2}\text{g}\right)÷\left(3.21\times {10}^{-3}\text{g}\right)=\frac{6.42\times {10}^{-2}\text{g}}{3.21\times {10}^{-3}\text{g}}\\ =2\times {10}^1\end{array}$

Interpretation Introduction

(c)

Interpretation:

The given problem needs to be solved in scientific notation and rounded off to the correct number of significant figure.

$\left(9.87\times {10}^4\text{g}\right)-\left(6.2\times {10}^3\text{g}\right)$

Concept introduction:

To add or subtract numbers in scientific notation, the numbers must have the same exponent.

Answer to Problem 126A

Round off to the correct number is $\text{9}\text{.25}\times {\text{10}}^4\text{g}$.

Explanation of Solution

Compute the following calculation.

$\begin{array}{c}\left(9.87\times {10}^4\text{g}\right)-\left(6.2\times {10}^3\text{g}\right)=\left(98700-6200\right)\text{g}\\ \text{=92500}\text{g}\\ \text{=9}\text{.25}\times {\text{10}}^4\text{g}\end{array}$