Q 01/05

What is helium's atomic number?

A) 1

B) 2

C) 4

D) 10

Answer · why

B) 2

2: helium's atoms are so light that the gas floats in air, which is why it fills party balloons, weather balloons and airships.

Q 02/05

Helium takes its name from the Greek word for what?

A) The Sun

B) Light

C) Laughter

D) Air

Answer · why

A) The Sun

The Sun, helios in Greek, gave helium its name because astronomers saw the element's yellow line in sunlight in 1868, decades before anyone found it o...

Q 03/05

To which group of the periodic table does helium belong?

A) The halogens

B) The noble gases

C) The alkaline earth metals

D) The alkali metals

Answer · why

B) The noble gases

The noble gases are helium's family, and it is so unreactive that chemists have never made an ordinary stable compound of it.

Q 04/05

By mass, about how much of the universe's ordinary matter is helium?

A) About 0.1%

B) About 2%

C) About 25%

D) About 99%

Answer · why

C) About 25%

About 25%: almost all of that helium was made in the Big Bang itself, before any star had formed.

Q 05/05

During what event in 1868 was helium's yellow spectral line first detected?

A) A great comet's passage

B) A transit of Venus

C) A large sunspot outbreak

D) A total solar eclipse

Answer · why

D) A total solar eclipse

A total solar eclipse over India let French astronomer Jules Janssen record a bright yellow line that was at first taken for sodium.