if oxygen is in a compound what would its oxidation number be

HESI A2

HESI A2 Chemistry Practice Test

1. If oxygen is in a compound, what would its oxidation number be?

A. 2
B. -2
C. 0
D. -1

Correct answer: B

Rationale: Oxygen typically has an oxidation number of -2 in compounds because it tends to gain electrons. This is due to its high electronegativity, which leads to oxygen attracting electrons towards itself in a chemical bond. Choice A (2) is incorrect because oxygen doesn't have a +2 oxidation number in compounds. Choice C (0) is incorrect as oxygen rarely has an oxidation number of 0 in compounds. Choice D (-1) is incorrect as oxygen's oxidation number in compounds is typically -2, not -1.

2. What is the correct order of the hierarchy of levels in the biological classification of organisms?

A. Kingdom, phylum, class, order, family, genus, and species
B. Phylum, kingdom, class, order, family, genus, and species
C. Order, phylum, class, kingdom, family, genus, and species
D. Kingdom, phylum, order, class, family, genus, and species

Correct answer: A

Rationale: The correct order of the hierarchy of levels in the biological classification of organisms is Kingdom, Phylum, Class, Order, Family, Genus, and Species. This order is based on the Linnaean system of classification, with each level representing a progressively more specific grouping of organisms. Choice B is incorrect because it starts with Phylum instead of Kingdom. Choice C is incorrect as it places Order before Phylum. Choice D is incorrect because it does not follow the correct order of the biological classification hierarchy.

3. Multiply 0.05 by 22 and express the result as a decimal:

A. 1.1
B. 0.11
C. 0.011
D. 0.0011

Correct answer: C

Rationale: When multiplying 0.05 by 22, you get 1.10. To express this result as a decimal, you move the decimal point two places to the left since there are two total decimal places in the question (one in 0.05 and none in 22), resulting in 0.011. Choice A (1.1) incorrectly adds a decimal place, choice B (0.11) incorrectly moves the decimal point only one place, and choice D (0.0011) adds an extra zero.

4. A set of temperature readings has a range of 5 degrees Celsius. What does this tell you about the data?

A. The average temperature is 5 degrees Celsius.
B. All temperatures are within 5 degrees of each other.
C. The difference between the highest and lowest temperatures is 5 degrees.
D. There are exactly 5 temperatures in the set.

Correct answer: C

Rationale: Option A is incorrect because the range of 5 degrees does not necessarily mean that the average temperature is 5 degrees Celsius. The average temperature could be any value within the range. Option B is incorrect because the range of 5 degrees does not mean that all temperatures are within 5 degrees of each other. It only indicates the difference between the highest and lowest temperatures. Option C is correct because the range of 5 degrees specifically refers to the difference between the highest and lowest temperatures in the set. This is a common definition of range in statistics. Option D is incorrect because the range of 5 degrees does not determine the number of temperatures in the set. The set could have more or fewer than 5 temperatures.

5. An inability to be lucid in the early morning means the person is unable to behave in which way?

A. Coherent
B. Speculative
C. Furtive
D. Animated

Correct answer: A

Rationale: An inability to be lucid in the early morning means the person is unable to behave in a coherent way. Lucidity refers to clarity of thought and coherence in one's behavior or speech. If someone is not lucid, they may be confused, disoriented, or unable to express themselves clearly. Therefore, the correct choice is A. Coherent. Choices B, C, and D are incorrect because being unable to be lucid does not necessarily mean the person is behaving in a speculative, furtive, or animated way.