Pretend you are a teacher preparing a quiz for the text I will provide. 
            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
            The output should be a ready-to-use list of dictionaries for the Python eval function:

            [

                    "question": "WRITE THE QUESTION HERE",
                    "options": ["A) OPTION_1", "B) OPTION_2", "C) OPTION_3", "D) OPTION_4"],
                    "answer": INDEX_OF_CORRECT_ANSWER_IN_OPTIONS_LIST,
                    "explanation": "EXPLAIN WHY THE ANSWER IS CORRECT"

            ]

            Text:
            lyst.  
➢ Setting reaction is addition polymerization reaction  no by-product. 
➢ But, a 2ry reaction → hydrogen gas,  
so it is recommended to wait at least 30 minutes, rather than have a pitted cast. 
104
 
 
Characters: 
➢  it is similar in many ways to condensation silicone. 
➢  except that it has much greater dimensional stability = to that of polyether.  
➢   its working time is more affected by temperature. 
➢  Presentation:  putty/ heavy/ medium / light / extra-low.  
Advantages: 
1. Excellent dimensional stability (no by-products)   
so pouring could be delayed up to 7 days.  
Multiple pours can be done without affecting accuracy. 
2. Available in all viscosities  allowing a variety of impression 
3. Hydrophilic brands are easier to wet the tissue & easier to pour  
(as surfactants are added to the paste)  
4. has good compatibility with gypsum. 
5. Easy to mix & handle. 
6. Automix available.  
7. Elastic recovery. 
8. Great accuracy. 
9. Short setting time. 
10. 
 Good tear resistance. 
Disadvantages: 
1. Moderate stiffness, i.e. the set material is stiffer > polysulfide,  
                                                         but less rigid < polyether. 
2. Pouring is difficult with earlier hydrophobic brands. 
3. The impression area must be dry to prevent inaccuracies in the impression. 
4. Earlier hydrophobic brands  evolve hydrogen gas upon reaction  a pitted cast, 
so pouring should be delayed for 24 hours to avoid voids in the poured cast  
(Recently to overcome this problem the manufacturer added palladium to absorbs 
hydrogen   pouring can be done after 15 minutes with no voids in the cast) 
5. Hydrophilic brands cannot be electroplated. 
6. Sulfur in latex gloves inhibits the setting reaction.  
➢ if the tissues are touched with gloved hands immediately before impression, 
➢  It has also been shown that sulfide & sulfide-chloride can be transferred from latex 
gloves to displacement cord. 
➢  which enables the transfer of these known inhibiting agents to sulcular tissues. 
105
 
 
 
A, Scanning electron microscope finding of gingival displacement cord 
contaminated by latex glove contact.   
Arrows indicate particles on surfaces & within fibers of displacement cord.  
B, Electron probe microanalysis of gingival displacement cord contaminated by 
latex glove contact.  The red patches are areas of sulfur element  
4) Polyether: 
➢ it has become popular because it only requires a stock tray & a single mix. 
Characters: 
X  The impression should not be immersed in disinfectant for > 10 minutes.  
➢ Since it's hydrophilic, it absorbs water, it should not be kept with the alginate. 
➢ Polyether is stable only if stored dry,  
because it absorbs moisture → significant dimensional change. 
Composition:  
1) base:                  2) accelerator: 
• Polyether             - Alkyl aromatic sulfonates 
• Fillers                   - Inert oils 
• Plasticizers          - Plasticizers 
Chemistry:  
• When base & accelerator are mixe

            Quiz: