The substance is followed by H2O
The given question is incomplete. The complete question is:
The combustion of propane (C3H8) in the presence of excess oxygen yields
and
When only 2.5 mol of
are consumed in order to complete the reaction, ________ mol of
are produced.
Answer: Thus when 2.5 mol of
are consumed in their reaction, 1.5 mol of
are produced
Explanation:
The balanced chemical equation is:

According to stoichiometry :
5 moles of
produce = 3 moles of 
Thus 2.5 moles of
will produce =
moles of 
Thus when 2.5 mol of
are consumed in their reaction, 1.5 mol of
are produced
Move anywhere and can be anywhere while it is in that phase
1. Energy can neither be created or destroyed.
2. Conduction. Putting a pot of water on a hot burner. Convection. Putting your wet shoes over an air vent to dry them quicker. Radiation. Sitting in front of the fire to warm your hands up.
3. renewable sources can be used again and again, but non renewable sources cannot.
4. I would recommend solar energy. I think solar energy should be considered because solar energy can be reused, and also because they can use it to power their houses and they wouldn't need fossil fuels to do so.
5. Turn off the lights and open the windows during the day and if something is left plugged into the wall and it is not being used, unplug it.
hope I could help!