<span>When a substance changes from one state, or phase, of matter to another we say that it has undergone a change of state, or we say that it has undergone a change of phase. For example, ice melts and becomes water; water evaporates and becomes water vapor.These changes of phase always occur with a change of heat. Heat, which is energy, either comes into the material during a change of phase or heat comes out of the material during this change. However, although the heat content of the material changes, the temperature does not.</span>
Explanation:
The important quantum-mechanical concepts associated with the Bohr model of atom are :
1. Electrons are nothing but particles that revolve around the nucleus in discrete orbitals.
2. Energy is associated with each orbital is quantised. Meaning electron in each shell will have energy in multiple of a fixed quanta.
Explanation:
a) 4P + 3O2 --> 2P2O3
b) The chemical reaction above limits the number of molecules of P2O3 produced for every 4 atoms of P.
A meander is best described as a bend or curve in a stream channel.
