Answer:
The spectra of the Sun and stars exhibited bright and dark lines called Fraunhofer lines. These were shown to be caused by elements emitting or absorbing light at specific wavelengths. Because each element emits or absorbs light only at specific wavelengths, the chemical composition of stars can be determined.
The correct answers are options C, that is, silver tarnishes and becomes black when exposed to oxygen, and option E, that is, diesel fuel burns when it is heated.
Chemical changes refer to the modifications in which the chemistry at molecular level is modified as the initial substance gets transformed into a new and different final substance. This change occurs with the dissociation of old bond and production of new bonds respectively.
Silver gets tarnished and becomes black when exposed to oxygen. This refers to a chemical change as silver a white and lustrous substance gets transformed into a tarnish black final substance. However, silver does not easily react with oxygen at usual circumstances. It easily reacts with sulfur comprising components in the air and generates black compound as Ag₂S.
Burning of diesel fuel when it is heated. Diesel refers to a mixture of hydrocarbons varying approximately from C₁₀H₂₀ to C₁₅H₂₈. When these hydrocarbons get burnt they generate novel substances, that is, carbon dioxide and water. Hence, it is also a chemical reaction.
Answer:
See explanation below
Explanation:
I found a picture of this exercise, to show you how to do this problem.
The first picture is the compound, and the second is the mechanism of reaction to do this claisen rearrangement.
Hope this helps
Answer:
1 A
3 main types of bond are
Ionic bond ( formed due to complete transfer of electron between atoms(
Covalent bond ( formed by mutual sharing of electron)
Metalic bond ( present in the metals due to mobile electrons)
1 B bond in CaO is ionic bond formation in attached image
1 C hydrogen bond with nitrogen is covelent NH3 ammonia is formed because a bond between two non metals is expected to be covalent
More their electronegativity difference between hydrogen and nitrogen is less than 1.7 that makes it covalent
Explanation:
