Which elements do hydrogen fuel cells combine to produce electricity? A. hydrogen and oxygen
B. hydrogen and carbon
C. hydrogen, oxygen, and nitrogen
D. hydrogen, carbon, and nitrogen
PLEASE HELP

Why was the sample heated in step 5? describe the chemical principles involved in the reasoning behind this step?

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

What best explains whether bromine (br) or neon (ne) is more likely to form a covalent bond? bromine forms covalent bonds because it has seven valence electrons, but neon has eight valence electrons and already fulfills the octet rule. bromine forms covalent bonds because it has many electron shells, but neon has only two electron shells and is tightly bound to its electrons. neon forms covalent bonds because it can share its valence electrons, but bromine has seven valence electrons and can gain only one more electron. neon forms covalent bonds because it has only two electron shells, but bromine has many electron shells and will lose electrons in order to fulfill the octet rule.