In the reaction __h2 + o2 → 2h2o, what coefficient should be placed in front of h2 to balance the reaction?
select one:
a. 1
b. 2
c. 3
d. no coefficient is needed

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8

12 is it do you think so