Which of the following are the units of the rate constant for a 2\({}^{\rm nd}\) order reaction given that concentration is measured in molarity and time in seconds:

W) M\({}^{-2}\)s\({}^{-1}\)

X) M\({}^{-1}\)s\({}^{-1}\)

Y) Ms\({}^{-1}\)

Z) M\({}^{-2}\)minutes\({}^{-1}\)
X) M\({}^{-1}\)s\({}^{-1}\)