Question
A trinitro compound, 1 , 3 , 5 -tris-( 4 -nitrophenyl) benzene, on complete reaction with an excess of Sn / HCl gives a major product, which on treatment with an excess of NaNO 2 / HCl at 0 ° C provides P as the product. P , upon treatment with excess of H 2 O at room temperature, gives the product Q . Bromination of Q in aqueous medium furnishes the product R . The compound P upon treatment with an excess of phenol under basic conditions gives the product S . The molar mass difference between compounds Q and R is 474   g   mol - 1 and between compounds P and S is 172 . 5   g   mol - 1 . The number of heteroatoms present in one molecule of R is [Use: Molar mass (in g mol-1): H = 1 , C = 12 ,   N = 14 , O = 16 , Br = 80 , Cl = 35 . 5 Atoms other than C and H are considered as heteroatoms]