if gas a has four times the molar mass of gas b you would expect it to diffuse through a plug

HESI A2

Chemistry HESI A2 Practice Test

1. If gas A has four times the molar mass of gas B, you would expect it to diffuse through a plug ___________.

A. at half the rate of gas B
B. at twice the rate of gas B
C. at a quarter the rate of gas B
D. at four times the rate of gas B

Correct answer: A

Rationale: When comparing the diffusion rates of two gases, according to Graham's law of diffusion, the rate of diffusion is inversely proportional to the square root of the molar mass. If gas A has four times the molar mass of gas B, the square root of the molar masses ratio (4:1) is 2. This means that gas A would diffuse through a plug at half the rate of gas B. Therefore, the correct answer is A, at half the rate of gas B. Choices B, C, and D are incorrect because they do not reflect the correct relationship between the molar masses and the rates of diffusion according to Graham's law.

2. The main idea of the passage is ___________.

A. The CDC keeps an eye out for new potentially threatening health issues
B. Children require several more hours of sleep per night than adults do
C. More people are staying up at night to surf the Internet or watch television
D. Lack of adequate sleep is becoming a major national health problem

Correct answer: D

Rationale: The main idea of the passage is that lack of adequate sleep is becoming a major national health problem.

3. Select the meaning of the underlined word in the following sentence. Quick action kept the disease from permeating the general population.

A. Conquering
B. Wounding
C. Deterring
D. Infiltrating

Correct answer: D

Rationale: In this context, the word 'permeating' indicates the process of spreading throughout or penetrating into. 'Infiltrating' is the most appropriate synonym for this meaning, as it captures the idea of the disease spreading into the general population. 'Conquering' (Choice A) means to overcome or defeat, which is not the meaning in this context. 'Wounding' (Choice B) means to cause injury, which is not relevant to the sentence. 'Deterring' (Choice C) means to discourage or prevent, which does not fit the context of the disease spreading.

4. What is the correct pronoun to complete the sentence?

A. Her
B. Hers
C. Best
D. More greatest

Correct answer: A

Rationale: The word 'her' is the correct choice because it serves as the object of the preposition 'at.' In this sentence, 'looked at' requires an object pronoun, making 'her' the appropriate choice. Option B, 'Hers,' indicates possession, which is not needed in this context. Options C and D are not pronouns and do not fit grammatically in the sentence.

5. What is another word for deferentially?

A. Imperfectly
B. Respectfully
C. Competently
D. Energetically

Correct answer: B

Rationale: The word 'deferentially' means showing respect or submission to someone. Therefore, the closest synonym for 'deferentially' is 'respectfully' as it reflects the attitude and behavior of showing respect towards others. The other choices are incorrect: 'Imperfectly' means with flaws or errors, 'Competently' means having the necessary ability or skills, and 'Energetically' means with energy or enthusiasm, none of which capture the respectful connotation of 'deferentially.'