Answer: 6.38 moles of 
are needed to react with 2.55 mol of 
Explanation:
The balanced chemical reaction for the combustion of ethyne is:
According to stoichiometry:
2 moles of require = 5 moles of
Thus 2.55 mol of require = 
moles of
Thus 6.38 moles of are needed to react with 2.55 mol of
Answer:
4.28x10^24 molecules
Explanation:
From Avogadro's hypothesis, 1mole of any substance contains 6.02x10^23 molecules. From the above, we understood that 1mole of H2O also contains 6.02x10^23 molecules.
1mole of H2O = (2x1) + 16 = 2 + 16 = 18g
Now, if 18g of H2O contains 6.02x10^23 molecules,
Then 128g of H2O will contain = (128x 6.02x10^23) /18 = 4.28x10^24 molecules
