Question

One mole of a chemical element contains approximately 6.02 × 1023 atoms. How many atoms are present in 4.6 × 104 moles of oxygen? Represent the answer in scientific notation. Round so the first factor goes to the hundredths place.
A.
2.77 × 10^27 atoms
B.
2.77 × 10^28 atoms
C.
27.7 × 10^27 atoms
D.
27.7 × 10^28 atoms

Answer 1

Answer:

B. 2.77 · 10^28

Step-by-step explanation:

The total number of atoms is ...

(6.02·10^23 atoms/mol)·(4.6·10^4 mol) = (6.02·4.6)·10^(23+4) atoms

≈ 27.7·10^27 atoms

≈ 2.77·10^28 atoms . . . . . . put in scientific notation form

_____

Scientific notation has one non-zero digit to the left of the decimal point and the exponent adjusted accordingly.

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Your calculator can help you figure this out. If necessary, put the display into scientific notation mode. (For numbers this size, it is usually not necessary.)

Answer 2

Answer: B.  $2.77\times10^{28\text{ atoms}}$

Step-by-step explanation:

Given : One mole  of a chemical element contains approximately $6.02\times10^{23}\text{ atoms}$

Then , the number of atoms present in $4.6\times10^{4}\text{ moles}$ is given by :-

$6.02\times10^{23}\times4.6\times10^{4}\\\\=6.02\times4.6\times10^{23}\times10^{4}$

Using exponents property:

$a^m\times a^n=a^{m+n}$

$=27.692\times10^{23+4}\\\\\approx2.77\times10^{23+4+1}=2.77\times10^{28\text{ atoms}}$