As the unit of rate constant is min−1 so it must be a first order reaction
k×t=2.303logA0/At
in 1 min 10 is inactivated so taking
A0=100At=90 in 1min
So k×1=2.303×log90100
=2.303×(log10−2log3)
=2.303×(1−2×0.477)
=0.10593
=105.93×10−3
Answer is 106