Final answer:
The student can conclude that the unknown liquid contains reducing sugars if the Benedict's test results in a color change after heating, and it contains starch if the iodine test causes a dark blue or black color change.
Step-by-step explanation:
When a student adds a glucose indicator (Benedict's solution) and a starch indicator (iodine) to separate beakers containing an unknown liquid and records the color changes that occur, they can determine the presence of specific carbohydrates in the liquid. If upon adding iodine to one beaker the solution turns a dark blue or black color, this indicates the presence of starch. Conversely, if after adding Benedict's solution to the other beaker and heating the mixture it changes to a green, yellow, orange, or red color, it indicates the presence of reducing sugars, such as glucose. Therefore, one conclusion the student might make about the unknown liquid based on these results is that the liquid contains the carbohydrate detected by the observed color change. If the solution with iodine turns dark blue or black, the conclusion is that starch is present. If the Benedict's test results in a color change to green, yellow, orange, or red after heating, the conclusion is that reducing sugars like glucose are present. It's important for the student to follow proper laboratory safety procedures while conducting these tests. This includes wearing goggles to protect the eyes from any splashing chemicals or heat exposures. It's a standard practice to wear protective equipment when dealing with reagents such as Benedict's solution and conducting tests that involve heating.