Answer: Let's see why
Pure solid and liquid compounds possess sharp melting and boiling points. Therefore, melting and boiling points of a compound can be used as a criteria of purity. ... Sometimes during cooling minute quantity of the substance (solid which is being purified) is added to the solution to facilitate the initial crystallisation.
Explanation:
Answer:
The ionization energy (in kJ/mol) of the helium ion is 21,004.73 kJ/mol .
Explanation:

Z = atomic mass
n = principal quantum number
Energy of the electron in n=1,

Energy of the electron in n = ∞

Ionization energy of the
ion:


To convert in into kj/mol multiply it with 

Neutrons actually don't carry an electrical charge, which is why they are called neutrons because they are "Neutral".
Answer:
a. 0.5 mol
b. 1.5 mol
c. 0.67
Explanation:
Fe3+ + SCN- -----> [FeSCN]2+
a. The ratio of the product to Fe3+ is 1:1. Meaning that if 0.5 mol of product was produced up then 0.5 mol of Fe3+ was used. Leaving 0.5 mol remaining at equilibrium
b. The ratio of the product to SCN= is 1:1. Meaning that if 0.5 mol of product was produced up then 0.5 mol of SCN- was used. Leaving 1.5 mol remaining at equilibrium
c. KC = 0.5/(0.5*1.5) = 0.67