Answer:
C) Krypton is a noble gas, so it was difficult for chemists to find it, as though it was a secret.
Explanation:
Answer: The atomic number
Answer:
False. Chemical changes are always physical changes
Food, Storage, and Structure
Answer: Using more fossil fuels
Explanation: Burning fossil fuels releases Green House gasses into the atmosphere, such as carbon dioxide. The carbon dioxide in the atmosphere traps in heat, which causes global temperatures to increase.