Its a change in state of solid to liquid
the reason is that in a solid state the molecules have little kinetic energy to move and so they have restricted movement and so it remains solid
once heat is applied the molecules gain enough energy to move and so they turn into a liquid and move according to the laws of physics
hope that helps
Dark colored moths survived better in the Industrial Revolution because their dark color helped them camouflage in soot. When the industrial revolution ended there wasn't as much soot, so the light colored moths now had a better chance of survival.
V(NaOH)*M(NaOH)=V(HCOOH)M(HCOOH)
35.43ml*0.1150m=20.00ml*M(HCOOH)
M(HCOOH)=0.2037m
hydrogen is the lightest element in the periodic table
There are 30 protons and 39 neutrons in the nucleus.
This must me the isotope of an element with an atomic mass close to 69 u.
The only candidates are Zn and Ga.
Zn has a zinc-69 isotope with mass 68.926 u.
Ga has a gallium -69 isotope with mass 68.925 u.
The isotope is probably

.
It has 30 protons and 39 neutrons.