Question

1. find $\frac{8.5\times10^{5}}{1.3\times10^{2}}$. write your answer in scientific notation
2. what is the mass of 75,000 oxygen molecules? express your answer in scientific notation. mass of one molecule of oxygen = $5.3\times10^{-23}$
3. find $(3.8\times10^{7})\times162$. write your answer in scientific notation.

Explanation:

Step1: Calculate the quotient of the coefficients

Divide 5.5 by 1.3: $\frac{5.5}{1.3}\approx4.23$

Step2: Calculate the exponent of 10

Use the rule $\frac{10^{a}}{10^{b}}=10^{a - b}$, so $\frac{10^{4}}{10^{3}}=10^{4 - 3}=10^{1}$

Step3: Combine the results

The result in scientific - notation is $4.23\times10^{1}$

for question 4:

Step1: Write the number of oxygen molecules in scientific notation

$75000 = 7.5\times10^{4}$

Step2: Multiply the number of molecules by the mass of one molecule

$(7.5\times10^{4})\times(5.3\times10^{-23})$

Step3: Multiply the coefficients and add the exponents

$(7.5\times5.3)\times10^{4+( - 23)}=39.75\times10^{-19}$

Step4: Adjust to proper scientific notation

$3.975\times10^{-18}$

for question 6:

Step1: Write 162 in scientific notation

$162=1.62\times10^{2}$

Step2: Multiply the numbers in scientific notation

$(3.8\times10^{7})\times(1.62\times10^{2})$

Step3: Multiply the coefficients and add the exponents

$(3.8\times1.62)\times10^{7 + 2}=6.156\times10^{9}$

Answer:

$4.23\times 10^{1}$