A 138110-4 mol of an unidentified gaseous substance effuses

Question

(a) 1.381×10^-4 mol of an unidentified gaseous substance effuses through a tiny hole in 89.2 s. 

Under identical conditions, 1.710×10^-4 mol of argon gas takes 82.2 s to effuse. 

What is the molar mass of the unidentified substance (in g/mol)?

(b) The percentage C by mass in the above unidentified substance is 83.2%. It may also contain H and/or O, but no other element. 

What is the molecular formula of the substance? 

(In typing this formula use the convention of C first, H second and O last. For example, C₆H₈O₂ would be C6H8O2.) 

(c) Under identical conditions, how many moles of cyclopropane (C₃H₆) gas would effuse in 93.6 s?