Answer:
Specific gravity of mercury is 13.56 and it is an unit-less quantity.
Explanation:
Mass of the mercury = m = 607.0 lb = 275330.344 g
1 lb = 453.592 g
Volume of the mercury = v = 

Density of the mercury = d=
d = 13.56 g/mL
Specific gravity of substance = Density of substance ÷ Density of water

Specific gravity of mercury :
(unit-less quantity)
On the other hand ammonia is a very dangerous chemical which has a pungent smell and effect the eyes of the user. Thus it kept always in the fume exhaust hood for storing and dispensing function.
The pH of ammonia buffer contains ammonium hydroxide (NH₄OH) and a salt of ammonia with a strong acid like (HCl) which produces, ammonium chloride (NH₄Cl) mixture. The evaporation rate of ammonia is so high at room temperature thus on opening of the buffer solution the ammonia get evaporated very fast and the concentration of ammonia decreases which affect the pH of the buffer solution.
Thus the reason to put ammonia buffer in fume hood is explained.
The correct name of the compound Mn3(PO4)2 is definitely the last option represented above <span>D. manganese(II) phosphate. I am pretty sure this answer will help you
</span><span>
</span>
The answer to your question is,
B) CaCl2
-Mabel <3