A student is baking a cake at home and has placed several ingredients on the countertop. She has scooped some baking soda into a measuring spoon. She accidentally knocks over a cup of vinegar and several drops spill onto the spoon with the baking soda. The baking soda begins to fizz where the vinegar spilled on it. When the fizzing stops, the student notices that about half the baking soda on the spoon is gone and a liquid is now on the spoon. What happened to the baking soda?

a. Evaporated into the air.
b. Melted into the vinegar.
c. Dissolves in the vinegar and forms a mixture.
d. Combines with the vinegar and produces a new gas.