A group of students combined different substances together during several experiments. Their observations are recorded on the chart below. 1. A blue liquid and a yellow liquid were mixed and it turned green

2. A solid substance dissolved in a clear liquid

3. Two room temperature liquids were mixed and the temperature increased

4. Two different liquids were mixed and began to separate and layer in a beaker

In which experiment did a chemical reaction likely occur?

1
2
3
4?