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

They are all full and don't need any more electrons in there outer shell.

Your answer is a just took the test

Sorry i dont understand the question can you rephase it?

Answer:             1.0  × 10⁻⁵ msolution:                     as we know ph is given as,                                    ph  = -log [h⁺]and,                                    [h⁺]  =  10^-ph    (1)putting value of ph in eq. 1,                                    [h⁺]  =  10⁻⁵                                    [h⁺]  =  1.0  × 10⁻⁵ m