a pure substance which atoms are of the same type is called.
A.mixture
B.Compound
C.Element
D. All of the above
example of noble gases are:
A.Hydrogen and helium
B.nobelium and Einsteinium
C.helium and Nean
D.magnesium and chlorine
the lightest gas is:
A.Helium
B. oxygen
C.Neon
D.carbon dioxide ​