For 10 points, name this lightest noble gas, with atomic number two and symbol He (H-E).
An alpha particle is a nucleus of this element, which has a filled 1s (ONE S) orbital but no p orbitals at ground state. After the Hindenburg disaster, this gas replaced hydrogen in zeppelins and blimps. Because the speed of sound in this gas is much faster than that in air, inhaling it causes a high-pitched voice. For 10 points, name this lightest noble gas, with atomic number two and symbol He (H-E).
An alpha particle is a nucleus of this element, which has a filled 1s (ONE S) orbital but no p orbitals at ground state.
helium [accept He before it is read]