What is the change in enthalpy for the following reaction? 2h2o2(aq) 2h2o(l) + o2(g) given: h2o: ∆h= -242 kj h2o2: ∆h= -609 kj a) -286 kj b) -572 kj c) 572 kj d) 286 kj

What rule is used to determine how many covalent bonds an element can form? a. the number of covalent bonds is equal to six c the number of covalent bonds is equal to five minus the group number plus the group number b. the number of covalent bonds is equal to eight d. none of the above minus the group number select the best answer from the choices provided