I think the charge is +2
Hope this helps
1 km is equal to 100,000 cm
![725km \times 100000cm \\ = 72500000 \: km .cm](https://tex.z-dn.net/?f=725km%20%5Ctimes%20100000cm%20%5C%5C%20%20%3D%2072500000%20%5C%3A%20km%20.cm)
and you need to divide it to 1 km so that you can get rid of the km.
boiling, salt water will separate the salt from the water through the physical change of water from a liquid to a gas, leaving you with just salt left over.
22-yes, they belong to the same group
23- they are metals
24-Atoms of group 1 elements all have one electron in their outer shell. This means Na and K have the same valence electrons.
25-Metals are solids at room temperature, therefore Na and K are solid.
26- mass number=A=235
Protons=z=92
Neutrons=mass number-protons
Neutrons=A-Z
Neutrons=235-92
Neutrons=143