The unit of rate constant for a zero order reaction is `s^(-1)`.

Explanation

Units of rate constant of the reaction ` = ("units of rate ")/("(concentration)")`
`L mol^(-1) s^(-1) = (mol L^(-1) s^(-1))/((mol L^(-1))^(a))`
Therefore the value of n is equal to 2.
Rate equation for the reaction is given as, rate ` = k [A]^(2)`.