False , it will make it lighter
So to balance an equation, you need to get the same amount of each type of element on either side of the --> . So you pretty much are given the subscripts in the equations and you need to add coefficients (just normal numbers) in front of any formula that needs it, keeping anything balance.

turns into

These coefficient numbers are the molar ratios, so 2 moles of KCl3 for every 3 moles of O2 so 1. 3:2
Then you can use these ratios of find out how many moles of one thing are needed if you are given the amount of another.

and use cross multiplication to solve for whatever you don't know
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Answer:
Over the past few decades, humans have released so many different chemicals into the air that they have changed the mix of gases in the atmosphere. ... In addition, the exhaust from cars, trucks, and buses releases nitrogen oxides and sulfur dioxide into the air.
Sublimation. It's basically, in simple terms, when a solid changes to a gas without going into liquid form.