The table shows the concentration of a reactant in the reaction mixture over a period of time.


Reactant Concentration
Time Concentration
0 s 1.8 M
210 s 1.2 M
450 s 0.8 M
580 s 0.6 M
720 s 0.4 M


What is the average rate of the reaction over the first 450 seconds?
1.7 × 10−3
1.9 × 10−3
2.0 × 10−3
2.2 × 10−3