The only one example of a chemical change would be:
B. Leaving cheese out to get moldy.
Because there is a chemical reaction.
Answer:
1,2 dichlorobenzene was used as the solvent for the diels alder reaction: <em>because the co elimination part of the reaction needs high temp and a high boiling point solvent such as 1,2 dichlorobenzene</em>
Explanation:
Diels-Alder Reaction is a useful synthetic tool to prepare cyclohexane rings. It is a process, which occurs in a single step that consists of a cyclic redistribution of its electrons. The two reagents are bond together through a cyclic transition state in which the two new C-C bonds are formed at the same time. For this to occur, most of the time, it is necessary a high temperature and high-pressure conditions. Since 1,2 dichlorobenzene has a boiling point of 180ºC is a good solvent for this type of reactions.
The correct answer is A. A test tube of zinc oxide. Zinc oxide is a compound which is a pure substance composed of two or more elements. They can only be separated or broken down into its individual elements or smaller compounds by chemical means. Therefore, the answer is a test tube of zinc oxide.
Answer: emission spectrum
Explanation:
