Question

Calculate the number of molecules in 18g of oxygen gas

Answer 1

since , 1 gram molecular mass of oxygen = 1mole of Oxygen gas
then
1mole of Oxygen gas =6.022×10^23 molecules
1 gram molecular mass of oxygen =32g
32g=6.022×10^23 molecules
1g=6.022×10^23 molecules/32
18g=6.022×10^23 molecules/32×18
=3.38×10^23 molecules Ans***
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