Do you agree or disagree that a chemical reaction always happens when 2 substances arw combined? provide evidence why or why not?

i disagree

Explanation:

i disagree because a chemical change (or chemical reaction, whatever you wanna call it) occurs when two substances are mixed together and transform into a third substance. Not all substances react chemically when mixed together, however. For example, some substances, when mixed together, remain simply a mixture of those two substances.

answer; i do believe the correct answer is (river); /// good luck

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6