Astudent is investigating the affect of different salts on melting points. four patches of ice of equal size are roped off and a different type of salt is poured on each, one receives table salt (nacl), one receives calcium chloride (cacl2), one receives potassium carbonate (kco3) and the fourth receives inert sand instead. each patch receives an equal amount of salt or sand. what could the student investigate?

Considering that the amount conditions of the ice and salt are controlled and we want to study the melting points.

They can only study the amount of time it takes  it to melt under each different types of salt and sand.

Explanation:

First of all, we need to understand something, they are going to study salt melting point on ice. All of them receive the same amount of ice and salt. Therefore, they can only study the amount of time that each salt takes to melt the ice. Because the dependent variable is the time the ice takes to melt under the effect of different types of salt and sand, while the independent variable is the ice. It is a comparison study without a control group because we are not using one as a base.