Answer:
Common combustion reactions break the bonds of hydrocarbon molecules,
Explanation:
the resulting water and carbon dioxide bonds always release more energy than was used to break the original hydrocarbon bonds. That's why burning materials mainly made up of hydrocarbons produces energy and is exothermic.
The moles can be defined as the mass of the substance with respect to molar mass. The moles of potassium nitrate is 1 mol.
<h3>How to calculate moles of a substance?</h3>
The moles of a compound can be calculated from:

The molarity can be defined as the moles of solute in a liter of solution.
The molarity can be expressed as:

The molarity of potassium nitrate solution is 2 M, and the volume is 500 mL.
The moles of potassium nitrate is given as:

The moles of potassium nitrate in 2 M, 500 mL solution are 1 mol.
Learn more about moles, here:
brainly.com/question/15209553
Answer is: four iron atoms <span>are reacting with every three molecules of oxygen.
Balanced chemical reaction: 4Fe + 3O</span>₂ → 2Fe₂O₃.
From chemical reaction: n(Fe) : n(O₂) = 4 : 3.
Ratios of atoms of iron and molecules of oxygen is 4 : 3..
There is four atoms of iron and six atoms of oxygen on both side of reaction.
Answer:
B. a bike braking
Explanation:
It involves friction! Hope this helps!