Dear aspirant

Hope you are doing well

Now let me go through your question

For the given rexn

2SO2+O22SO3

Initial moles ;         1.5        1            0

At eqm :           1.5−2x  1−x     2x          (let us suppose)

Now given that conc. of SO3 at eqm =0.35 mol/L

⇒2x=0.70⇒x=0.35                     ( the container is of 2L)

Now,  KC=[SO2]2[O2][SO3]2

=(1.5−2x)2(1−x)(2x)2

⇒KC=(21.5−0.7)2×(21−0.35)[20.7]2

=0.8×0.8×0.650.7×0.7×2= 2.35Lmol−1

hope it will help you

Thank you