Question

Two of most unique elements on the periodic table are hydrogen and helium. What makes them so unique and removed from the other groups on the periodic table?

a: Unlike all other elements, hydrogen and helium are gases

b: Unlike all other elements, hydrogen and helium are not considered metals

c: Unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons

d: Unlike all other elements, hydrogen and helium have very limited properties

Answer 1

I don't like any of these choices; however, the best choice seems to be d.
a CAN'T be right since several other elements are gases (F2, Cl2, O2, N2 etc).
b CAN'T be right since several other elements are not considered metals (See examples in the previous choice).
c CAN'T be right. Mg, Ca, Sr, Ba, Ra all have two valence electrons.
d is the only one that isn't wrong but, in my opinion, that doesn't make it a good statement.