Which evidence is an indication that a chemical reaction has occurred? A) melting of a substance
B) formation of a gas
C) boiling of a substance
D) freezing of a substance

21. consider the following chemical reaction: n2+ o2 2 no if 10.0 g of n2 reacts with excess oxygen then how many grams of no can be formed? a) 10.7 g b) 21.4 g c) 32.9 g d) 42.8 g page 4 of 8

What happened to the amount of carbon dioxide in the atmosphere from 2010–2017?

Which terms are used to identify pure substances