In nuclear fission reactions, what causes the atom's nucleus to become unstable?
A. Control rods being inserted into the nucleus
B. Extreme temperatures released by fuel rods
O C. The absorption of a free-moving neutron by the atom's nucleus
O D. The nucleus absorbing freely moving protons

electron microscopy and scanning tunneling microscopes gives us a greater understanding of atoms by being able to see the atom itself, and lets us see some atomic reactions.

explanation:

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3

you need to have a picture of the atom that way we can answer it