Give one advantage and one disadvantage of using hydrogen as fuel​

Word equation for k(s)+h2o(l) yield koh(aq) + h2(g)

Answer explain why it is not possible to deduce a complete order of reactivity.

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