Initial-rate data for the gas-phase reaction between A and B at 350 K are provided.
Experiment [A] (M) [B] (M) Initial rate (M·s⁻¹)
1 0.10 0.10 1.2 × 10⁻⁴
2 0.20 0.10 2.4 × 10⁻⁴
3 0.20 0.20 4.8 × 10⁻⁴
Assuming the reaction occurs in a single elementary step, determine the stoichiometric coefficients of A and B in that step.