In the combustion process using excess oxygen, each mole of methane results to 1 mole of co2 while ethane produces 2 moles of Co2. Under same conditions, these can be translated to volume. Hence the total volume absorbed is 10 cm3 + 20 cm3 = 30 cm3.
Answer: There are 
atoms in 24 moles of Fe.
Explanation:
According to the mole concept, 1 mole of a substance contains 
atoms.
Therefore, atoms present in 24 moles of Fe are calculated as follows.
Thus, we can conclude that there are atoms in 24 moles of Fe.
Thus, sound will travel at a slower rate in the denser object. If sound waves of the same energy were passed through a block of wood and a block of steel, which is more dense than the wood, the molecules of the steel would vibrate at a slower rate. Thus, sound passes more quickly through the wood, which is less dense.
For the answer to the question above, asking to w<span>rite the complete balanced equation for the reaction between aluminum metal (Al) and oxygen gas (O2)and You do not need to make the subscripts smaller.
My answer would be,
</span><span>4Al(s) + 3O2(g) --->2 Al2O3(s)
</span>
I hope this helps.
