What is the approximate solubility of potassium nitrate at 90°C

What type of reaction is zn + cucl2 → cu + zncl2?

What is a metal replacement reaction

Observation and experimentation have led many scientists to accept a theory about the origin of the universe. this theory is called the big bang theory. scientific evidence collected and observed by scientists around the world suggests that the universe is ever expanding from a hot and dense initial state. what makes this a scientific theory? (2 points)