An element X forms an iodide (XI3) and a chloride (XCl3). The iodide is quantitatively converted to the chloride when it is heated in a stream of chlorine: 2XI3+3Cl2→2XCl3+3I2 If 0.6000 g of XI3 is treated, 0.2832 g of XCl3 is obtained.

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Ch4 and ph3 are both covalent since they are composed both of non-metals.    ch4 is non- polar because of  london forces and has a geometry of tetrahedral  ph3 , on the other hand, is umbrella shaped polar and has dipole-dipole intermolecular force (imf) . since ph3 is polar, it has a stronger imf   

Answers are 1,2,4 its correct on edgenuity.