Reaction Order

The initial concentration of hydroiodic acid is 100 mmol/L but after 500 s it is 17 mmol/L. What is the rate? (note the products of this reaction are hydrogen and iodine gas)

The following initial rate data was collected for the reaction, 2 NO + O$_2$ $\longrightarrow$ 2NO$_2$

[NO$_2$]$^X$[O$_2$]$^Y$

The following initial rate data was collected for the reaction, CH$_3$Br + OH$^-$ $\longrightarrow$ CH$_3$OH + Br$^-$

B. What is the rate constant?

The following initial rate data was collected for the reaction, A + B + C $\longrightarrow$ products

What are the reaction orders with respect to the reactants?