Helium
/hˈiliəm/
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Definition
(noun) The second-lightest chemical element (symbol He), with an atomic number of 2 and atomic weight of 4.002602, a colorless, odorless and inert noble gas.
Sentence Examples
Jupiter is a planet principally composed of hydrogen and helium.
Helium, neon, argon, krypton, xenon and radon are noble gases.
CEFR Practice Quiz
The colorful party balloons were filled with ____ so they would float high in the air.