which of the following is not an allotrope of carbon

HESI A2

Chemistry HESI A2 Practice Test

1. Which of the following is not an allotrope of carbon?

A. Diamond
B. Graphite
C. Fluorine
D. Buckminsterfullerene

Correct answer: C

Rationale: The correct answer is C: Fluorine. Allotropes of carbon are different forms of the same element. Diamonds, graphite, and buckminsterfullerene are all allotropes of carbon. However, fluorine is a separate chemical element and not an allotrope of carbon. Therefore, fluorine does not belong to the group of carbon allotropes.

2. What is a mole?

A. 6.02 x 10^23
B. 1.00 x 10^24
C. 6.02 x 10^22
D. 6.02 x 10^25

Correct answer: A

Rationale: A mole is a unit used in chemistry to represent Avogadro's number, which is approximately 6.02 x 10^23. This number corresponds to the number of particles (atoms, molecules, ions) in one mole of a substance. Choice A, 6.02 x 10^23, is the correct answer as it accurately defines a mole. Choices B, C, and D provide values that are not equivalent to Avogadro's number, making them incorrect answers.

3. What are the horizontal rows of the periodic table called?

A. Periods
B. Families
C. Groups
D. Columns

Correct answer: A

Rationale: The correct answer is A: Periods. Rows in the periodic table are called periods. They are arranged horizontally from left to right and represent the energy levels of the elements. Each period starts a new energy level or shell, indicating the number of electron shells an element has. Choices B, C, and D are incorrect. Families and groups refer to vertical columns in the periodic table that share similar chemical properties, while columns are vertical arrangements of elements known as groups or families.

4. Which of these elements has the greatest atomic mass?

A. Au
B. Ba
C. I
D. W

Correct answer: D

Rationale: Among the elements listed, Tungsten (W) has the greatest atomic mass. The atomic mass of Tungsten is approximately 183.84 atomic mass units (amu), while the atomic masses of the other elements listed are as follows: Gold (Au) is around 196.97 amu, Barium (Ba) is approximately 137.33 amu, and Iodine (I) is about 126.90 amu. Therefore, Tungsten (W) has the greatest atomic mass out of the given elements. Gold (Au) has a higher atomic mass than Barium (Ba) and Iodine (I), making choices A, B, and C incorrect.

5. When balanced, the reaction Fe + Oâ‚‚ â†’ FeO will be?

A. 2Fe + 2Oâ‚‚ â†’ 3FeO
B. 4Fe + 6Oâ‚‚ â†’ 6FeO
C. 2Fe + 3Oâ‚‚ â†’ 2FeO
D. 4Fe + 3Oâ‚‚ â†’ 2FeO

Correct answer: C

Rationale: To balance the chemical equation Fe + Oâ‚‚ â†’ FeO, the coefficients needed are 2 for Fe and 1 for O. Therefore, the balanced equation becomes 2Fe + Oâ‚‚ â†’ 2FeO, which translates into 2Fe + 3Oâ‚‚ â†’ 2FeO. This corresponds to option C. Choice A has the incorrect number of oxygen molecules. Choice B has an incorrect number of Fe atoms on the product side. Choice D also has an incorrect number of Fe atoms on the product side.