To convert from Kp to Kc, you need this formula---> Kp= Kc (RT)^Δn, where Δn= gas moles of product- gas moles of reactants. since you did not give a reaction formula, I can't calculate Δn. but all once you find it out. just plug it.
Kp= Kc (RT)^Δn------------------> Kc= Kp/[(RT)^Δn]
Kp= 5.23
R= 0.0821
T= 191 C= 464 K
Δn= ?
Kc= 5.23/ (0.0821 x 464)^Δn= ???
True because certain fabric will catch on fire