Question

calculate the mass of oxygen molecules when no. of molecules is 3×10^21. [O =16].​

Answer 1

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Answer 2

Given,

$number \: of \: molecules = 3 \times {10}^{21}$

No.of moles=no. of molecules/Avagadro number=

$3 \times {10}^{21} \div 6.022 \times {10}^{23}$

=4.9 moles

Now, no.of moles=given mass/molar mass

4.9=w/16

w=4.9×16=78.4

mass of oxygen molecules=78.4g