The reaction SO2Cl2→SO2+Cl2, is a first order gas reaction with k=2.2×10−5s−1 at 573 K.
Thus by using first order reaction ,
k=2.303tlog[A]0[A]
log100[A]=2.2×10−5×60×902.303
log100[A]=118.8×10−32.303
log100[A]=51.6×10−3=0.0516
100[A]=1.12
[A]=89.3%