A student has a sample of solid calcium. It is shiny and metallic looking. He squeezes a pipet of concentrated sulfuric acid onto the calcium. Bubbles are produced and the calcium appears to disappear. The test tube gets hot. What kind of change occurred?

Physical change

Explanation:

There are two types of changes: physical change and chemical change. Physical change is defined as the change that changes the physical appearance of the substance and do not affcet the chemical composition of the substance whereas chemical change causes changes in the chemical composition of the susbstance.

The given example shows physical change because solid calcium undergoes sublimation. process in which a solid substance changes into gaseous phase directly without undergoing liquid phase.

Hence, the correct answer is "Physical change".

the correct answer is:

a. formation of precipitation