Final answer:
In a reaction rate experiment involving magnesium and hydrochloric acid, a test tube is used to contain the reaction, and a syringe may be used to measure liquid reagents or gases produced, thereby both apparatus are necessary.
Step-by-step explanation:
In an experiment testing the rate of reaction between magnesium and hydrochloric acid, both a test tube and a syringe may be used. The test tube serves as the container where the reaction will take place. It ensures that the reactants are confined to a small space and can be easily observed.
The syringe could be used to measure and add specific amounts of hydrochloric acid to the magnesium, or to measure the volume of gas produced, if the reaction produces a gas such as hydrogen. Thus, the correct answer to the question would be C. Both 1 and 2.