A pure crystalline substance is a substance with an almost perfect regular and periodic pattern in a solid state. This makes this type of substance a hard one compared to an amorphous substance which is soft because of the irregular pattern within.
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Answer: Refrigerator and fire extinguisher
Explanation: Refrigerator:An evaporator fan draws air from the refrigerator and blows it over the evaporator coils. The liquid refrigerant absorbs heat from the air and the air blows back into the refrigerator at a lower temperature, cooling the refrigerator. The liquid refrigerant starts to vaporize as it heats up and moves to the compressor.
Fire extinguisher:They work by smothering the fire: when you put a layer of powder or foam on the fire, you cut the fuel off from the oxygen around it, and the fire goes out. Carbon dioxide (CO2) extinguishers contain a mixture of liquid and gaseous carbon dioxide (a nonflammable gas).
To determine the mass of CO₂, the following must be known :
- the molar mass of CaCO₃
- the mole ratio of CaCO₃ to CO₂
- the molar mass of CO₂
<h3>Further explanation</h3>
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Decomposition of CaCO₃
CaCO₃ ⇒ CaO + CO₂
Given the mass of CaCO₃, so to determine the mass of CO₂ :
1. Find the mol of CaCO₃ from the molar mass of CaCO₃

2. Find the mole ratio of CaCO₃ : CO₂(from equation = 1 : 1)

3. Find the mass of CO₂ from the molar mass of CO₂

Ok, I will help you answer but it is very hard to read could you enlarge it first?
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