Q 01/05

The word 'atom' comes from the ancient Greek 'atomos', which described matter as being what?

A) Eternal

B) Uncuttable

C) Weightless

D) Invisible

Answer · why

B) Uncuttable

Uncuttable is what 'atomos' meant, and the name stuck even after 1897, when the discovery of the electron showed that atoms have smaller parts after a...

Q 02/05

A proton is roughly how many times heavier than an electron, which is why the nucleus holds nearly all an atom's mass?

A) About 18

B) About 180

C) About 1,800

D) About 18,000

Answer · why

C) About 1,800

About 1,800: the measured ratio is 1,836 to one. Yet the two particles carry exactly equal and opposite charges, which is why one proton and one elect...

Q 03/05

Which radioactive substance with a 12-year half-life makes exit signs and watch hands glow with no power source?

A) Polonium

B) Radon

C) Americium

D) Tritium

Answer · why

D) Tritium

Tritium is hydrogen with two neutrons. Sealed in glass tubes, it fires off beta particles that strike a phosphor coating, which glows for years withou...

Q 04/05

On average, how long does a neutron last outside an atomic nucleus before it decays into a proton?

A) About 15 seconds

B) About 15 minutes

C) About 15 hours

D) About 15 years

Answer · why

B) About 15 minutes

About 15 minutes: a free neutron is slightly heavier than a proton, so it can decay into one, shedding an electron and an antineutrino. Locked inside ...

Q 05/05

The name for the atom's dense centre, adopted by Rutherford in 1912, is a Latin diminutive of the word for what?

A) Fig

B) Nut

C) Peach

D) Grape

Answer · why

B) Nut

Nut is nux in Latin, and 'nucleus' means little nut, or kernel. Biology got there first: botanist Robert Brown named the cell's nucleus in 1831, some ...