Answer:
When a solid changes into a gas, it is called sublimation.
Explanation:
Answer:
0.01744 M is the hardness of the groundwater.
1,744 ppm is the hardness of the groundwater in parts per million of calcium carbonate by mass.
Explanation:

In = Indicator
Concentration of calcium ion in groud water = 
Volume of ground water = 
Concentration of EDTA solution = 
Volume of EDTA solution = 



![[CaCO_3]=[Ca^{2+}]](https://tex.z-dn.net/?f=%5BCaCO_3%5D%3D%5BCa%5E%7B2%2B%7D%5D)
So. ![[CaCO_3]=0.01744 M](https://tex.z-dn.net/?f=%5BCaCO_3%5D%3D0.01744%20M)
0.01744 M is the hardness of the groundwater.
0.01744 Moles of calcium carbonate are present in 1 Liter of solution.
Mass of 0.01744 moles of calcium carbonate =

1 g = 1000 g
1.744 g = 1.744 × 1000 mg = 1,744 mg

The hardness of the groundwater in parts per million :

1,744 ppm is the hardness of the groundwater in parts per million of calcium carbonate by mass.
Atomic mass silicon = 28.085 u
1 mol Si ---------------- 28.085 g
? ------------------------ 245 g
245 x 1 / 28.085 =><span> 8.72 mol</span>
<span>answer A</span>
If i had to answer i would choose a hope this helps
Answer:
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.
Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation.
Explanation: