1. A chemistry class is experimenting with iodine to see which common white powder items will react and make the iodine change color. Which item listed will have a chemical reaction with iodine?(1 point)
A. salt
B. cornstarch***
C. baking soda
D. powdered sugar
2. When performing a scientific investigation on an unknown substance, how can an indicator help you determine if the substance is a starch?
A.The indicator will change the smell of the substance
B.The indicator will change the color of the substance.***
C.The indicator will change the color of the substance.
D.The indicator will change the state of the substance.
3. A student has an unknown powder and wants to determine what it is. Based on appearance, the student believes it is baking soda. When performing the vinegar test, what can the student expect to happen if it is baking soda?
A. it will turn a blue black color
B.it will turn into a solid glass like substance
C.it will crystalise into a sugar like substance
D. it will bubble and foam***
4.A student is performing a Benedict’s test on an unknown substance. The student adds the reagent (the chemical required to make a color change), and nothing happens. Which conclusion can the student make?
A. The substance is not glucosed based
B. The test was inconclusive because the student needed to also test with iodine or vinegar.
C.The test was inconclusive because the student forgot to add heat.***
D.The substance is glucose based.
5 answers
Potential users of these answers need to hope that the same questions are always used -- and in the same order. In these days of online testing, questions and answer choices can easily be changed from test to test -- and often are to thwart cheaters!
Correct!
Reason: Starch is a common white powder that will have a color change when reacting with iodine molecules, often used in lads to detect starch, or starchy substances.
2. The indicator will change the color of the substance.
Correct!
Reason: Just as the reason above, the color helps out a lot! They use iodine to see if the color will change.
3. it will bubble and foam
Correct!
Reason: When Vinegar and baking soda reacted to each other they become foamy and are used a lot for the volcano experiment.
4. The test was inconclusive because the student forgot to add heat.
Correct!
Reason: Look up this, it will tell you everything about the test.
Summer Research Program for Science Teachers
Barbara Lillien
Identifying Food Nutrients
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