Consider the following reaction: 2NO_2(g) + Br_2(g) → 2NO_2Br(g) What is the rate constant k? ​[Image description: Expt. 1: [NO_{2}]_{o} M = 0.0010; [Br_{2}]_{o} M = 0.0020; Initial rate (M s^{-1}) = 2.4 x 10^{-5} Expt. 2: [NO_{2}]_{o} M = 0.0010; [Br_{2}]_{o} M = 0.0030; Initial rate (M s^{-1}) = 3.6 x 10^{-5} Expt. 3: [NO_{2}]_{o} M = 0.0020; [Br_{2}]_{o} M = 0.0020; Initial rate (M s^{-1}) = 9.6 x 10^{-5} Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a. 6000 M^{−2}s^{−1} b. 12,000 M^{−2}s^{−1}