The electron configuration of aluminum, atomic number 13, is (Ne) 352, 3p1. Aluminum is in period...
3
2
13
6

the answer is either b or c

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.