Question

when sodium metal is added to water, an orange flame is observed on the metal surface. based on this observation, what can best be concluded?
a physical change occurs because the metal gets smaller
a chemical reaction occurs because the liquid becomes cloudy
a chemical reaction occurs because heat and light are given off
a physical change occurs because vapor is released into the air

Explanation:

A chemical reaction is characterized by the formation of new substances and often accompanied by signs like heat, light, gas evolution, etc. When sodium reacts with water, the orange flame (light and heat) indicates a chemical reaction. Physical changes do not involve the formation of new substances and typically do not have such energetic manifestations.

Answer:

C. A chemical reaction occurs because heat and light are given off