Mixture is the right answer
Pure, crystalline solids have a characteristic melting point, the temperature at which the solid melts to become a liquid. The transition between the solid and the liquid is so sharp for small samples of a pure substance that melting points can be measured to 0.1oC. The melting point of solid oxygen, for example, is -218.4o<span>C.</span>
10% solution means=
= 
= 100 mg/mL
If the dentist inject 0.3 mL, that is equal to 0.3× 100 mg.
If the dentist inject 0.3 mL, that is equal to 30 mg.
So, as anesthetic procaine hydrochloride is often used to deaden pain during dental surgery. the compound is packaged as a 10.% solution (by mass; d = 1.0 g/ml) in water. When our dentist
injects 0.30 ml of the solution, 30 mg of procaine hydrochloride (in milligrams) is injected.
If solutions of nh4cl(aq) and nh3(aq) are mixed, the ions in the resulting solution that would be the spectator ions in any acid-base chemistry occurring in the solution would be the chloride ions. The mixture is a common buffer of ammonia and ammonium chloride. NH4Cl is a salt that is soluble in water dissociating into NH4+ and Cl-. The chloride ions are the spectator ions while NH4+ ions would be the conjugate acid for the buffer solution. Buffer solutions are solution which would resist change in pH when acid or a base is being added to the solution. The equilibrium reaction of the buffer solution in this problem would be
NH3 + H2O = OH– + NH4+
In the reduction-oxidation reaction given, Cu is reduced because it gained 2 electrons, on the other hand H2 is oxidized because it gained one electron. I hope this helps.
