Only someone who truly knows and understands this, tell me if the electron configurations are right :

cobalt= [ar] 4s^2 3d^7
gallium= [ar] 3d^10 4s^2 4p^1
rhodium= [kr] 4d^8 5s^1
lanthanum= [xe] 5d^1 6s^2
europlum= [xe] 4f^7 6s^2
thulium= [xe] 6s^2 4f^13
ytterblum= [xe] 6s^2 4f^14
polonlum= [xe] 6s^2 4f^14 5d^10 6p^4
curium= [rn] 5f^7 6d^1 7s^2
rutherfordium= [rn} 5f^14 6d^2 7s^2

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.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

i don't know people like to fight everywhere rip.