balancing chemical equations\nc₃h₈ + o₂ → co₂ + h₂o\nmultiple - choice question\nwhich element(s) should we…

Brief Explanations:

When balancing chemical equations, it is a common practice to start with elements other than oxygen ((O)) and hydrogen ((H)). In the given equation (C_3H_8 + O_2\rightarrow CO_2 + H_2O), carbon ((C)) and hydrogen ((H)) are present in the hydrocarbon ((C_3H_8)) on the left - hand side. Since (O) is present in multiple substances ((O_2), (CO_2), (H_2O)) and balancing (O) can be more complex if done first, we start with either (C) or (H).

Answer:

C. (C), H. (H)