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 chemical reaction occurs because the liquid becomes cloudy.
a physical change occurs because the metal gets smaller.
a physical change occurs because vapor is released into the air.
a chemical reaction occurs because heat and light are given off.

Explanation:

Cuando se agrega sodio a agua, se produce una reacción química. La presencia de una llama (que implica emisión de calor y luz) es una evidencia de una reacción química. Los cambios físicos no producen calor y luz como evidencia principal.

Answer:

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