human
Question: Which is a chemical change?

Choices:
A) Element 1 is hammered into a thin sheet.
B) Element 2 is heated and turns into a liquid.
C) Element 3 turns a greenish color as it sits in air.
D) Element 4 is ground up into a fine, slippery powder.
gpt
The correct answer is 2: Element 3 turns a greenish color as it sits in air..