ENTC 281 question n answers graded A+ 2023

ENTC 281Why was machine manufacture of horn combs often unsuccessful? - correct answer Pieces of horn were not flat or uniform in thickness. Why weren't daguerreotype cases made from horn or horn powders? - correct answer Horn does not flow easily and consequently it does not pick up fine details in a mold Casein comes from - correct answer Milk curd Moderately nitrated nitrocellulose is called - correct answer Pyroxylin What is the difference between collodion and moderately nitrated nitrocellulose? - correct answer Collodion is a thin film of moderatly nitrated cellulose What is the difference between parkesine and celluloid? - correct answer Parkesine was made with *pyroxylin* and various solvents. The *solvents* evaporated can caused shrinkage. Celluloid was *pyroxylin powder* and *gum camphor*. After seasoning to remove any water, the celluloid *did not shrink or warp like the Parkesine.* Bakelite comes from a chemical reaction between ? and ? - correct answer Phenol and formaldehyde. A bond between two carbon atoms is a ? bond. - correct answer Covalent Chemical A CH3 group is called a ___ group. - correct answer Methyl