Which an element that exist into two form

One of the few xenon compounds that form is cesium xenon heptafluoride (csxef7). how many moles of csxef7 can be produced from the reaction of 13.0 mol cesium fluoride with 12.5 mol xenon hexafluoride? csf(s) + xef6(s) csxef7(s)

A100 kmol/h stream that is 97 mole% carbon tetrachloride (ccl4) and 3% carbon disulfide (cs2) is to be recovered from the bottom of a distillation column. the feed to the column is 16 mole% cs2 and 84% ccl4, and 2% of the ccl4 entering the column is contained in the overhead stream leaving the top of the column. calculate the mass and mole fractions of ccl4 in the overhead stream, and determine the molar flow rates of ccl4 and cs2 in the overhead and feed streams. 12. mw_ccla- 153.82; mw_cs2-76.14.

Which is the solubility product expression for caf2(s)?  [ca2+]/[f–]2  [ca2+][f2–]  [ca]+[f]2  [ca2+][f–]2