According to the following reaction, how much energy is evolved during the reaction of 72.5 g Cl2?  (Assume that B2H6 is present in excess)             B2H6 (g) + 6 Cl2 (g)  →  2 BCl3 (g) + 6 HCl (g)         ΔH°rxn = -1396 kJ

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

Astudent is asked to identify and element that is pale yellow brittle solid and does not conduct electricity. at which location in this periodic table would the element most likely be found?

How many valence electrons are in atom of radon?