Rev 4. Finish the equation and give the typ
1. 231 Pa →
91
192 Ir +
77
Fission or fusion

not fission, the answer is fussion

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.