In a double covalent bonds there are 4 valence electrons that are shared.
Answer:Since dinosaurs are thought to be over 65 million years old, the news is stunning - and more than some could tolerate. After the AOGS-AGU conference in Singapore, the abstract was removed from the conference website by two chairmen because they could not accept the findings. Unwilling to challenge the data openly, they erased the report from public view without a word to the authors. When the authors inquired, they received this letter:
Explanation:
i do not own my copyrights
The matter is going to have to be in a <em>plasma </em>state! =)
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.
